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Full text of "The geology of the Coromandel subdivision, Hauraki, Auckland"

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To accompany Bulletin -N° 4, CoromcoicUl Subdivision , ffcturaki Division. -, Auckland Land District. 




C\ Koruengcu Islets 
Q Needle, 




JAMES MACKINTOSH BELL 



GEOLOGICAL MAP OF 

OTAiA 

SURVEY DISTRICT 

Scale of Chain s 

40 o ao u 

1 ' — ' ' — > ' — ' ' — ^ I - 



Reference 

Reads shown thus = 

Tracks ,, _ 



TrigonoTnetricaJL Stations- 

Swamp 

Water Races 

Tram, lines 

Jilines or Wbrlajigs 



_ C @»/ef/' 



Compiled, from, data obtained from. theZands and Survey Department , 
and surveys executed by Colin, Fraser and- J.HAdams 
of the Geological Survey Branch of the Mines Department. 



Reference to Geolo g ical Colou r s and S igns — 
Sedimentary 

Tokatea Hill j Argillites and grauwackes with inter- ] p re . Jurassic 

Series I stratified beds of igneous materials. J 

Manaia Hill j Argillites fcrsuwackes.grits.and fine |j urass j c 

Series | conglomerates I 

Torehina Series ( Conglomerates . sandstones, shales with ) Lower Eocene _ 
■I scams . Iimestones- 



^ Unconsolidated ( River terraces, river beds. sea ] Pre-Pleistocene.^ 

$ or poorly con- I beaches, drifting sands. \ Pleistocene, and) 

J? -solidated debris [ talus slopes. .1 Recent. J 

Igneous 

Tertiary rocks ofSecond Period - semi- basic Miocene | 

(Beeson's Island Series) i 

Tertiary rocks ofThird Period' - acidic Pliocene | 



*/<v\ 



Compiled and drawn by G.EHarrLs.Aygust 1907 



To accompany Bulletin W 4, Ccrcmandd Subdivision .Hauraki Division .Auckland Land District. 



— Reference to Geolo g ical Colours and Si fcns — 

Sedimentary 

Moehau Series _ Arfcillitea and fcrauwackes Pre- Jurassic. . 

Manaia Hill Series i *<*'»'*«. Jrauweches. grits and 
Vine conglomerates 

Torehine Series j ^tf ™"*'' •■ 

Unconsolidated (River terraces, river bads, sea ) Pre-Pleisi 

or poorly con- (beaches, drifting ! 

solldated debris I slopes. ) and Recent 

Tertiary rocks of 'First Period' Eoeeno?_ _ 

Tertiary rocks of Second Period Miocene? 

Intrusive rocks of various periods 

Veins (V^l 

Outcrops with observed strike end dip I 




JAMES MACKINTOSH BELL 

Geological Map of 

,. .0 

AND 

w 

SURVEY DISTRICTS 

Scale of Chains 

' pTT H H H "h- T 

Reference — 

Reads shctrr 

Tracks „ _ - 

TrigonernetrtcaL Stations _ ,, _ . 

Wata-rolU „_- 

Afines ■* Old Workings o. 

Compiled, from data obtained from, the Lands and Survey Dept 
and survey* executed by JMBell.CFraaer.E J.Webb, and D.VAUen, 
of the Geological Survey Branch, of the Mines Department. 



:'■->■;-„.._.-,>., ft jy ,,„■-. r .i ,l ._,.,• /'■'■■■ 



To accompany Bulletin N$ Q, Coromandel Subdivision. , Hawaii Division, Auckland Land District. 




To accompany BulUUnNZ 4. Corcmaridel Subdivision , HcuuJ-aki Division .Auckland Land District 




£ SOO below see level 



— Section along Line AB, Moehau & Harataunga Survey Districts. 




Section alon g Line CD E, Harataun g a & Coromandel Survey Districts 




F" 500 below see level 



Section along, Line FCH , Coromandel & Harataunga Survey Districts 




Section along Line JK, Coromandel Surve y District 




J^ SOO below sea level 



- '.:~ --~~??~^-rr-^^y77^\- 




JAMES MACKINTOSH BELL 



Section along Line KL, Otama Survey District 



Natural Scale ■ 



Drawn by QEHarris. Octr/307 



Reference to Geological colours 

Sedimentar y . Ig neous . 

Tokatea Hill lArglllites and grauwacke* wiTh inter - 1 f> _ Juross , c | ~ =\ 

Series 1 stratified bedb of igneous materials. " ■ ,, r „ ,<,, 

W»ho u S.nes. Ar*ll,t„ and ira^acte ..do .^ Tort ""? ""^ ° f Flre " *™>~~ "PP'^«*™ '» 

SJ"" |c A ^!„tV.tr aCk6S - 6 "'''' n '' f ' ne | Ju "™' --■ Tertl.ryrook, ofWrnriod 1 I 

' (Beeson's Island Series) I 

Torehine Ser..^tf<^ Eocene | T.S. | Tertiary rocks of Third ftmodL. 

Unconsolidated (River terraces, river beds, sea IPre-Pleistocene .1 , 

or poorly coruoU benches . drifting sands, Pleistocene, }— [ Intrusive igneous rocks of various per 

-idated debris [talus slopes )and Recent. ' 




pepai'tmtmt (o 




of "ptftrtes. 



NEW ZEALAND GEOLOGICAL SURVEY 

ij. M. BELL. Director. 



ho-^ 



BULLETIN No. 4 (New Series). 



THE GEOLOGY 



OK l II I 



COEOMANDEL SUBDIVISION, 

HAUEAKI, AUCKLAND. 



COLIN FRASER, 

l-T\ I) HY 

JAMES HENRY ADAMS. 



[BSl ED I NUKH THK AITHOKITY OF THK HON JAMES McGOWAN, M1NIBTBR OF MINKS 




NEW ZEALAND 
BY AUTHORITY: JOHN MACKAY. GOVERNMENT PRINTER. WELLINGTON. 



190*3 



Digitized by the Internet Archive 

in 2013 



http://archive.org/details/geologyofcoromanOOfras 



Ill 



LETTEK OF TRANSMITTAL. 



Geological Subve* Office, 

Wellington, 1st November, 1907. 

Sir — 

1 have the honour to submit herewith Bulletin No. 4 (new series) 

of the New Zealand Geological Survey. 

This Bulletin covers a report on the geology <>f the Coromande] Sub- 
division, Eauraki, Auckland, by Mr. Colin Fraser, Mining Geologist, assisted 

by Mr. .lames Hcnrv Adams. 

The volume comprises 15 1 pages of letterpress. It contains 1 1 maps 

and -2 sheets of sections, and is illustrated by 33 plates. 

I bave the honour to be, 
Sir, 
Your obedient servant, 

J. M. BELL, 



Director. 



Hon. James McGowau, 

Minister of Mines, 

Wellington. 



CONTENTS. 



Letter of transmittal 



Chapter I 



Introduction 

Area described in this bulletin 
Officers connected with field-work 
Acknowledgments 

Conditions of geological work, and method of con 
ducting field operations 



Towns and settlements. . 
Means of communication 

History of mining in t he Coromands] subdivision 
Mineral production 

Industries other than mining and quarrying 
Agriculture . . 









Page 








iii. 


. — Gen 


brat. Information. 






Page 

1 


Fauna 




Page 
. . 4 


2 


Flora 




5 


2 


Climate 




.. 7 


3 


Scenery 




..8 


i- 


Literature 




9 


. 3 








II. — General Culture. 






. 12 


Industries other t 


ban mining 


and quarrying - 


13 


ti a a, </. 






14 


Timber 




. . 20 


. 18 


Kauri-gum . 




. . 20 


. 19 


Flax 




.. 21 


19 


Fishing 




..21 



Sequence of formations 
i ieologioal history 



• 'muter III. — (tin. ink en thk Geology. 

..22 General structure of the several formations 
. . 23 



Chapter IV. — Physical Ghoqraphy. 



General physiographic features 

The main divide and its subsidiary ridges 
('(.) The Moehau aeotion 
(6.) The Cabbage Hay Waiau section . 

(r.) The Waiau Mahakirau section 
The outlying ridges and groups of hills 
The lowland* 

Features of the general ooast-line 
Islands 
Streams 

{a.} Streams draining the northern and narrower 
portion of the subdivision 



27 
28 
28 
29 

2!» 

30 
30 
31 
32 

32 



Streams- continued. 

(b.) Streams draining the southern ami wider 

portion '>f the subdivision 
(r.) Streams draining the Kuaotunu Peninsula .. 
Id.) Streams draining the ares lying to the east 
of Whitianga Estuary 

Springs 

Hot spring 
Cold springs 



25 



33 Water-power 



35 
36 

37 

37 
37 
38 

38 



Chapter V. Prf.-.Ikrass[c and 
Introduction . . 10 

The Tokatea Hill Series . . . . . . 41 

General statement . . . . . . 41 

Age and correlation . . . . 41 

General distribution . . 41 

General structure . . . . 12 

Petrology . . . . . . . . . . 43 

(a.) Argillites and grauwackes 13 

(6.) Acidic tutfs ;tn d tufaeeous mudstones . . 43 
(c.) Quartz-sericite rocks (altered rhyolitesT) . . 4.5 

(d.) Contemporaneous rhyolites .. ..45 

The Moehau Series . . . . . . 46 

General statement . . 46 

Age and correlation .. .. .. I'i 

General distribution .. .. .. . . 4fi 



Jurassic Stratutktj R<>rK>. 
The Moehau Series— continued. 
General structure 
Petrology . . 
Argillites 
Grauwaokee 

The Manaia Hill Scries . 

General statement 

Age and correlation 

General distribution 

General structure 

Petrology 

Conglomerates 

Grits and grauwackes 

Arcillites 



47 
47 
47 

48 

48 
48 
48 
50 
51 
51 
51 
52 
52 



Introduction . . 
( leneraJ distribution 
( ieneral structure 



• 'llAI'TKK \'l. — 'I'll K ToBEHINB Series. 
Page 



53 
53 
54 



Ago and palaeontology 
Special areas . . 



Page 
-.4 
.')5 



General statement 
Fluviatile deposits 
Lacustrine deposits 



ChAPTEB VII. — LuOSEI.Y COHSOLIDATED AND UNCONSOLIDATE]) DtBRIS. 

59 Littoral deposits 

. . 59 Talus and wind-blown deposits . . 

CO Earth-movements of Quaternary tunes 



60 

01 

til 



Content 

(1.) Tertiary volcanic rocks of the 
General statement 



Chatter VIII. 
. . 62 



First Period 



(A.) The rhyolites 

Distribution 

Structure, and conditions of eruption 

Petrology 
(B.) The andesites and dacites 

Distribution 

Structure, and conditions of eruption 

Petrology 

Megascopic characters 
Structure of the matrices 
General character of the phenoorysts 
(u.) Hypersthene andesites 
(b. ) Augite andesites 
(e.) Pyroxene andesites .. 
(d. ) Hornblende andesites 
(e.) Dacites 
Propylitisation of the volcanic rocks 

(2.) Tertiary volcanic rocks of the " Second Period " 

(Beeson's Island Series) 
General statement 
Age and correlation 
Distribution 

Structure, and conditions of eruption 
Petrology 

Megascopic characters 

Character of the matrix and the pheno- 
orysts 

(a.) Hypersthene andesites 

(h.) Pyroxene andesites 

(c.) Hornblende andesites ... 

(d. ) Dacites 



63 
63 

63 

64 
64 
64 
64 
65 
65 
65 
67 
67 
67 
68 
70 
71 
71 
72 
73 
74 

75 

75 

76 
77 
77 
80 
80 

80 
81 
82 
83 
83 



-Igneous Rocks. 

(3.) Tertiary volcanic rocks of the "Third Period 
General statement 

Age 

Distribution 

Structure, and conditions of eruption 

Petrology 

( ieneral statement 

(n.) Pumiceous tuffs 

(b.) Pumiceous agglomerates 

(c.) Pumiceous breccias 

(d.) Banded and spherulitic rhyolites 

(4.) Intrusive rocks of various periods 
( ieneral statement 
(n.) The semi-basic intrusive* 
Distribution 
Age 
Petrology 

Quartz-biotite diorite 
Quartz diorite 
Diorite porphyrite . . 
Hornblende porphyrite 
Pyroxene porphyrite 
The dacites 
The andesites 
(6.) Acidic intrusives 

(ieneral statement 
Distribution and structure 
Age 
Petrology 

(5. ) Succession of lavas 

(6.) Igneous rocks as building-stones 
Diorite 

Pumiceous tuffs and breccias 
Rock for roadmaking 



S3 
83 
84 
84 
84 
85 
85 
85 
85 
86 
86 

87 
87 
87 
87 
88 
89 
89 
90 
90 
90 
92 
92 
92 
94 
94 
94 
94 
94 

95 

96 
96 

97 
97 



Chapteb IX. 

Introduction . . . . . . . . 98 

Periods of mineralisation . . . . 98 

The circulation-channels or vein fissures . . 99 

The mineralising agents .. .. ..100 

Rock-alteration connected with mineralisation . . 100 

Mineralogy of the ore and gangue minerals . . 101 

Structure of the vein-material . . . . . . 105 

Oxidation .. .. .. .. 105 

The ore- shoots .. .. .. ..106 

The origin of the gold and silver . . . . 107 

Distribution of the veins . . . . . . 107 



-Mineral Veins. 
Detailed description of special areas 
Veins of the Colville Survey District 
Veins of the Moehau Survey District 

Hope Creek 

Sorry Mary Creek 

Ohinewai Creek 

Ongahi Creek 
Veins of the Harataunga Survey District 

Veins of Tangiaro Creek 

Veins of Umangawha Valley 

Veins of Matamataharakeke 



108 

108 
108 

108 
108 
100 
109 
109 
109 
110 
110 



VI 1 



Detailed description of special areas — continued 

Veins of the Harataunga Survey District — continued. 
Veins of Mangatu (reck .. .. .. 110 

Veins of Mataiterangi (reck and Bay View Mine 
(Kennedy's Hay) .. .. ..Ill 

Veins of Omoho Creek .. .. ..Ill 

Veins and mining claims of the Hauraki special 

area . . . . . . . . ..Ill 

Locality and general features of the area 111 

l Seologioa] formation . . . . ..Ill 

Mining claims . . . . . . ..Ill 

The Hauraki and Hunker's Hill Claims .. Ill 

The Welcome Find and Hauraki Freehold 
Claims . . ..IK") 

The Golden Pah, Hauraki No. 2, and Hauraki 
South ( laim- . . . . . . 115 

Veins and mining claims of the Kapanga special 

..11") 
Ijocality and general features of the area . . 115 

Ceologioal formation .. .. ..116 

Mining claims . . . . ..lib 

The Old Kapanga Claim .. . . .116 

Old Scotty's Claim . . . . 118 

Other areas . . . . . . ..118 

Veins and mining claims of the Tokatea SuOOeSS 

I! Mine . . . . . . . . ..119 

Locality and general features of thi 119 

Ceolo'_'ical formation .. . . 11!) 

(a.) Tokatea " Big Reef " .. ..119 

(b.) Veins of Tokatea Hill and vicinity .. 121 

Royal Oak and Tokatea Claim .. 121 

Harbour View and Pride of Tokatea < Slain 12.1 

W< -t Tokatea Claim . . .123 

Queen of the North (Monte Cristo) claim 121 

(r.) The veins of the Suooees Hill and vicinity 124 

Veins of the Waikoromiko sped .. 124 



Chapter IX. — Mineral Veins — continued. 

l'Bge 



Page 
Detailed description of special areas continued 

Veins of the Waikoromiko special area, — continued. 

The Four-in-Hand and Tandem Claims .. 124 

Veins of the Old Whangapoua Claim (Lillis) . . 12.5 

Veins of Preece's Point special area . . . . 125 

The "prospects" of Little Paul's Creek Valley .. 126 

The veins and mineralised rhyolites of Aitken, Pe- 

tote, and Tiki Creeks .. ..126 

Veins of Tiki Hill and Matawai Valley .. ..128 

"Prospects" of the Manaia Valley .. .. 12!i 

Veins of Opitonui Valley .. .. 129 

Veins of Mahakirau Valley .. .. ..130 

Veins of Battery and Day Dawn (recks .. 130 

Veins of Jubilee Creek and vicinity .. .. 131 

Veins of Materangi, Murphy's Hill, Owera, and Moe- 

wai .. .. ..131 

Materangi Bidge Veins .. .. .. 132 

Murphy's Hill „ .. .. . . 132 

Owera Veins . . . . . . 132 

Moewai ( 'laim . . . . . . . . 132 

Veins and mining claims of the Kuaotunu special 

area . . . . . . . . . . 133 

Locality and general features of the ii .. 133 

Geologioal formation .. .. .. 133 

The veins and mining claims .. .. .. [33 

Veins of the Bald Spur and vicinity .. 133 

ln\ iota Claim . . . . . . . . 135 

Veins and siliceous sinters of Waitaia Ridge .. 135 

Waitaia Claim . . . . . . 135 

Aorere < hum . . . . . . . . 136 

1. olden Anchor Claim .. .. .. 136 

New Mint Claim . . . . 136 

( tther claim- . . . . . . 136 

The sflioeous sinters of Waitaia Ridge .. 136 

Veins of Whauwhau Creek .. .. 137 

The " prospects" of the Purangi special area . . 137 



Chapter X. — Examination of Fi.i viwiie Qbavsu for the LoOATIOll OF possum, f. Minkiui.-hkauim: Vreas. 



Introduction 

Results of prospecting operations — 
Colville and Moehau Survey Districts 
Harataunga Survey District .. 



138 

13s 
139 



Results of p rospe cting operations — continued. 
Coromandel Survey Distriol .. 141 

1 M una Survey District . . . . . . 144 



Chapter XL — Resume of the EOOHOKN Possibilities of the CoBOKANDEL Si hdiviso .\. 
Introduction .. .. .. .. U5 Building and ornamental stones 

The future prospects of gold-silver mining .. I4"> Limestone 

Metalliferous deposts other than tiold-silver veins . . 14S Coal 



148 
14s 
148 



Ylll 



LIST OF ILLUSTRATIONS ACCOMPANYING BULLETIN N< 



Plate. 

Coromandel 

I. Castle Rock, from the Waiau Valley 
Castle Rock, from the south-west 

II. Tokatea Hill, from the south-east .. 

East slope of Tokatea, Kennedy's Bay in ihe distance 

III. Kuaotunu Valley, looking northeast from Try Fluke Battery 
Kuaotunu Valley, showing northern termination of Bald Spur 

IV. Waitaia Ridge and Black Jack Hill, from Materangi 
Te Tutu volcanic neck, viewed from the eastward 

V. Shakespeare Cliff, Meroury Bay 
Whitianga Rock 

VI. Coast-line north-east of Waitaia Ridge 

Materangi Bluff, with Black Jack Hill in the distance 

VII. Micro-photograph of spotted acidic tuff or tufaceous mudstone 

VIII. Micro-photograph of altered rhyolite .. .. ... 

IX. Inoceramus Haastii (Hochstetter) .. 
Belemnites, sp. 

X. Micro-photograph of conglomerate, Manaia Hill Series, Manaia Hill 

XI. Micro-photograph of conglomerate, Manaia Hill Series, Waiau River 

XII. Micro-photograph of conglomerate, Manaia Hill Series, Waiau River 

XIII. Micro-photograph of silicifled area in conglomerate (Plate XII), Manaia Hill Series, Waiau 

River 

XIV. Micro-photograph of conglomerate, Manaia Hill Series, Waiau River 
XV. Micro- photograph of conglomerate, Manaia Hill Series, Matawai Creek 

XVI. Micro-photograph of conglomerate, Manaia Hill Series, Kuaotunu 

XVII. Micro-photograph of conglomerate, Manaia Hill Series, Kennedy's Bay 

XVIII. Torehine, showing strata of 'Porehine Series . . . . . . . , ] 

Moehau Range viewed from Tawhetarangi . . . . . . . . f 

XIX. Micro-photograph of coralline limestone, Torehine 

XX. Micro-photograph of micropoecilitic hyphersthene andesite 

XXI. Micro-photograph of micropoecilitic hypersthene hornblende andesite 

XXII. Micro-photograph of propylitised andesite 

XXIII. Hillocks of stratified tuffs and agglomerates . . . . . . I 

Stratified tuffs and agglomerates, forming hills . . . . . . f 

XXIV. Te Kouma Harbour . . . . . . . . . . . . | 

Trigonometrical Station RR, Kennedy's Bay . . . . . . . . } 

XXV. Micro-photograph of hornblende dacite 

XXVI. Micro-photograph of hyalopilitic hyphersthene andesite 

XXVII. Micro-photograph of pumiceous fine-grained agglomerate 

XXVIII. Micro-photograph of quartz diorite 

XXIX. Summit of Tokatea Hill, showing Harbour View Mine, old prospecting drives, &c. 

XXX. Eastern section of the property of the Old Hauraki Gold-mines (Limited) 

XXXI. New Four-in-Hand Company's Battery, Waikoromiko .. . .1 

Royal Oak Battery, Tokatea Hill . . . . . . . . . . . . J 

XXXII. Siliceous-sinter terrace on Waitaia Ridge, Kuaotunu .. .. .. ..i 

Siliceous-sinter terrace on Waitaia Ridge, Kuaotunu . . . . . . ) 



Facing Page 
Frontispiece. 



14 



30 
32 

33 

44 
45 

48 

52 
52 
52 

52 
52 
52 
52 
52 

56 

57 

74 
74 
74 



79 

82 
83 
86 
90 
98 
114 

125 
136 



Table showing Proposed Classification' of Formations 



Facing Page. 
23 



IX 



MAPS ACCOMPANYING BULLETIN No. 



1. New Zealand, showing land districts and divisions 

2. Hauraki Division, showing survey districts .. 

3. Map showing the principal veins of the Coromandel Goldfield 

4. Map showing mining claims (existing or abandoned) in vicinity of Coromandel 

5. Plan of quartz veins of the Hauraki Group of mines, Coromandel 

6. Plan showing principal veins of the Old Kapanga Gold Mine 

7. Plan showing principal workings of Royal Oak and Hauraki Associated Gold Mines 

8. Map showing mining claims (existing or abandoned) in vicinity of Kuaotunu 

9. Geological map of Colville, Moehau, and Harataunga Survey Districts 

10. Geological map of Coromandel Survey District 

11. Geological map of Otama Survey District 



Facing Page 
x 

X 

104 
108 
112 

118 
122 
132 

In portfolio. 



SECTIONS ACCOMPANYING BULLETIN No. 4. 



1. Diagram showing profiles of principal streams 

2. Geological sections .. 

(a.) Section along line A B, Moehau and Harataunga Survey Districts 
(b.) Section aloDg line C D E, Harataunga and Coromandel Survey Districts 
( c.) Section along line F G II, Coromandel and Harataunga Survey Districts 
(d.) Section along line J K, Coromandel Survey District 
(e.) Section along line K L, Otama Survey District 



Facing Page 

38 
In portfolio. 




166 



By Authority : John Mackay, Government Printer. 




COLVILLE 



STRYPHENA 




PLAN OF 

HAURAK! DIVISION 

SHOWING SURVEY DISTRICTS 

Districts dealt vyitTi in. BuUettrv NZ 4- 
coloiweci tfuis 

ENGLISH MILES 



SOUTH PACIFIC 



CEAN 




Bay of Plenty 



^CAMBRIDGE 
Cambridge — Hf\j 



R T Ft U A 



D I V J S I O N 



By Authority : John Uackay, Government Printer. 



BULLETIN No. 4 (NEW SERIES) 



THE GEOLOGY 



OF THE 



COKOMANDEL SUBDIVISION, 

HAURAKI. AUCKLAND. 



CHAPTER I. 



GENERAL INFORMATION. 



Introduction . . . . . . 1 Fauna 

Area described in this Bulletin .. .. 2 Flora .. 

Officers connected with Field-work .. % 2 Climate 

Acknowledgments .. ..3 Scenery 

Condition- oi Geological Work and Method Literature 

of condm tiiiir Field Operations.. ',i 



PaRe 
4 



Introihc I ION. 

The Hanrak'i Division lies between latitudes 36 south and 38 south on the eastern Bide of the 

North Island of New Zealand. 

This division includes within its boundaries the Cape Colville Peninsula,* a contiguous portion of 

the mainland to the southward, from which tin; peninsula has its extension, and several small islands 
each located within short distances of the coast-line of the peninsula. The Great Barrier Island 
(106'8 square miles) and the Great Mercury [aland (6*67 square miles) are the most important of these 
insular areas. 

The division is hounded to the north and east 1 . \- the wind-swept waters of the Pacific Ocean. 
To the westward its peninsular shore-line is washed by the sheltered waters of the Hauraki Gulf and 
Firth of Thame-. From the south shore of the latter physical feature- an arbitrary line extending due 
southward marks the western boundary of this portion of the area. This line, which is 52 miles iti 
length, passes across the alluvial plains west of the Piako River, and terminates a short distance south 
of the Town of Cambridge. From the southern extremity of this meridional line, a line passing due 

lor 34 miles, then north-north-east for 3 miles to Mount l'uwhenua, then from Mount Puwhenua 
due east to the shores of the Bay of Plenty, a distance of about 45 miles, determines the boundary 
hetween the Hauraki Division and the Rotorua or Hot Lakes Division. This southern boundary-line 
throughout its whole course traverses undulating and hilly country. The Hauraki Division is thus 
roughly triangular in shape, and, together with the several small outlying islands, covers an extent 
of 2.952 - 97 square miles. 

The Hauraki Division constitutes at the present time the most important gold-mining area in 
New Zealand. In its southern portion is located the Waihi Mine, which now ranks among the world's 
greatest gold-producers, while further north lie the mining centres of Thames and Coromandel, both 

♦This peninsula is also known as Coromandel Peninsula, and as Hauraki Peninsula. 
1— Coromandel. 



famous for the great bonanzas of their auriferous quartz veins. The area from a geological point of 
view is a wonderfully interesting one, presenting on a grand scale all the evidences of vulcanism and 
attendant solfatarism of former geological times. A Tertiary volcanic complex, referable to several 
periods of eruptive activity, overlies folded and denuded sedimentary formations. The extrusion of 
the volcanic materials, which form masses of considerable thickness and areal extent, has been inti- 
mately connected with orogenic movements. 

The consideration of its structure, petrology, and ore-deposits, shows that the Hauraki area 
presents many striking resemblances to the Washoe, Cripple Creek, and Tonopah mining districts of 
the United States of America, and to the ancient mining-field of the Hungarian province of Transyl- 
vania in Europe. The further study of the Hauraki veins and their surroundings may be expected 
to throw additional light on the important and fascinating problems connected with ore-genesis. 

Area described in this Bulletin. 

The Hauraki Division has for the purposes of convenience in survey been marked off into four 
subdivisions. These, considered in order from north to south, have been named the Coromandel sub- 
division, the Thames subdivision, the Waihi subdivision, and the Tauranga subdivision. Geographically 
considered, the principal mining centres of the Hauraki Mining District fall into three areas, and these 
areas practically coincide with the first three of these subdivisions — namely, Coromandel, Thames, 
and Waihi. 

The Coromandel subdivision, which consists of the Survey Districts of Colville, Moehau, Hara- 
taunga, Coromandel, and Otama, as laid out by the Lands and Survey Department, is the area described 
in this bulletin. It forms the northern portion of the peninsula and stretches southward from Cape 
Colville for a distance of 28 miles, to a line extending due east from a point near Kirita Bay on the 
western coast-line, to Hot Water Beach on the eastern coast-line. The Coromandel subdivision as 
thus defined covers an area in all of 307*89 square miles. 

The Great Barrier, the Great Mercury, and certain other outlying islands are not included in the 
area considered in the present report. The examination collectively of these and all the other islands 
in the neighbourhood of the peninsular coast-line can be more conveniently undertaken apart from 
the 'mainland at a later date, before the preparation of the completed monograph on the Hauraki 
Division. 

Officers connected with the Field-work. 

The field examinations upon which this bulletin is based have extended over a period of some 
seventeen months (October, 1905 - March, 1907), and are referable to the individual work of several 
investigators. 

Dr. J. M. Bell, Director of the Geological Survey, initiated the survey in October, 1905, when he 
conducted the field-work in the extreme north-western portion of the area. From this date to the 
end of the year the work had his personal supervision. 

The senior writer of this bulletin, who joined the field party on the 7th of November, 1905, assumed 
charge of operations on the departure of the Director from the field, and, with the exception of the 
period from February to August, 1906, when assisting in the field elsewhere and in office-work in con- 
nection with the preparation of Bulletin No. 1 (Hokitika Sheet, North Westland), he was continuously 
engaged in this capacity in the Coromandel subdivision. 

For the first eight months of the year 1906, Mr. E. J. H. Webb, and since that period Mr. J. H. 
Adams, both now Assistant Geologists of the Survey, performed the duties of assistants on the Hauraki 
field staff. During the six months' absence of the senior writer from the field Mr. Webb continued 
the operations during a rather inclement winter season, in an area lying to the east of the main mountain 
divide and extending from Port Charles to the southern watershed of Kennedy's Bay Valley. 

In addition to the several permanent officers of the Geological Survey Staff, Mr. D. V. Allen, 
Director of the Coromandel School of Mines, was engaged to assist in the field-work for two terms of 
six weeks each. During the first of these periods Mr. Allen was engaged in the study of the Cabbage 
Bay district, while in the second period the examination of the Te Pungapunga and Whangapoua 
Valleys was assigned to him. 



3 

Acknowledgments. 

A great number of the scenic illustrations contained within the pages of this report are from photo- 
graphs taken by Mr. Alexander McKay, while the micro-photographs illustrating the petrography 
of the area are the expert work of this geologist. For these favours, and for valuable information 
afforded the writers by Mr. McKay, who has an intimate knowledge of the geological conditions in 
the Hauraki area, grateful appreciation is formally expressed. 

To Dr. J. S. Maclaurin, Colonial Analyst, and his staff, all the analyses quoted in this bulletin, 
except where stated to the contrary, are referable, and for the expeditious manner in which the various 
reports were furnished, the writers wish to record their cordial thanks. 

The thanks of the Geological Survey Department arc especially due to the private mine-owners 
and to the attorneys, legal managers, and mine-managers of the several companies controlling the 
mining interests within the boundaries of the Coromandel subdivision. All were without exception 
most courteous in placing at the disposal of officers of the Survey the plans of their respective mines, 
and in facilitating in every way the examination of the underground and surface workings. 

In connection with the mine-workings at present abandoned, much accurate information was 
voluntarily supplied by Mr. John Reilly, C.E., land and mining surveyor, a favour which is gratefullv 
acknowledged. 

Conditions of Geological Work and Method of conducting Field Operations. 

The general conditions within the Coromandel subdivision are not so favourable for geological 
investigation as might at first sight be expected from considerations of its latitude and physiography. 

The volcanic material which takes such a large part in the structure of the peninsular mass is 
subject to rapid surface decomposition : the crests and -lojie< of the ranges are therefore covered with 
a comparativelv thick mantle of disintegrated rock, which effectively conceals thi contacts of the various 
formations. As regards vegetation, the thick matted undergrowth which characterizes much of the 
New Zealand forest is here greatly in evidence, and constitutes a very effective barrier to geological 
investigation and mineral-prospecting. Forest vegetation continues to the greatest elevations met 
with in the subdivision, so that the traverse even of the crests of the wind-swepi Moehau Range 
(elevation 2,000 ft. to 2.935 ft.), was, owing to the almost impenetrable nature of the mountain scrub, 
a matter of considerable difficulty. 

Very fair natural sections are exposed along the coast -line, and this was therefore examined in 
detail. Along the coastal belt, however, the older volcanic rocks, which constitute the principal auri- 
ferous series, are overlain by the products of a later period of volcanic activity, and are therefore 
seldom encountered. 

The beds of the main streams and of their tributaries afford the best outcrops for aiding the geolo- 
gist in the mapping of the various formations. Where, however, these watercourses traverse areas of 
altered and consequently easily eroded andesitn rocks, outcrops are often rare, owing to the large amount 
of recent debris in course of transport. Within the actual mining centres the examination of all avail- 
able underground workings, and also of the plans in possession of the various rnining companies, afforded 
much information. It is very unfortunate, however, that during the progress of the present survey 
the mining industry of this district was experiencing one of its periods of temporary depression, and, 
consequently, in no claim was mining being carried on below the level of the ground-water, owing to 
the cessation of pumping operations. Seeing that very many of the rich ore-shoots, which have made 
some of these mines famous, occurred below the water-level, it is a matter of regret that further geological 
examination in this direction was precluded. 

Much of the information in this bulletin, relating to nuning conditions in the lower levels, has 
been gleaned from various official jplans J and records, and from reliable persons who ,'iave had 
direct connection with actual mining operations. The recorded observations of previous geological 
investigators have also been of value in this connection, as well as the senior writer's intimate 
personal acquaintance with the mines during a period when active operations were in progress. In 
the carrying-out of the field-work every effort has been made to make the examination as thorough 
1" — Coromandel. 



as possible. The accurate location of the geological and topographical features necessitated a great 
a mount of traversing. The ordinary county map on a scale of 80 chains to the inch, as issued by 
the Lands and Survey Department, was used as a basis for the mapping, but an inspection of the maps 
accompanying this bulletin will show that the topographical information has been greatly amplified by 
the present survey. 

The coast-line, which has a total length of some 190 miles, was surveyed in detail. The main 
streams, together with many of their tributaries, were carefully traversed, and, in addition to an in- 
spection of the various rock-outcrops encountered therein, a careful examination of the stream-debris 
was carried out, for the purpose of delineating the areas in which auriferous veins may reasonably be 
expected to occur. 

Although, as already indicated, rock-outcrops on the more elevated country are few and far-between, 
ascents were made of all the conspicuous peaks of the main divide. The greater part of the main 
water parting between the peaks, in addition to many of the subsidiary ridges and spurs, was also 
traversed. 

Fauna. 

The Coromandel subdivision, in common with all other parts of New Zealand, contains no indi- 
genous mammalian life, the short-tailed bat (Mystacops tuberculatus) excepted ; but it is one of the 
few localities that shields from extinction that wonderful and interesting reptile the tuatara lizard 
(Spkenodon punctatus), the sole living representative of the reptilian fauna of Triassic times. On the 
peninsula, or mainland portion of the Hauraki Division, this giant lizard is believed to be extinct, but 
it is found on the Great Mercury, and on other of the outlying islands included in the subdivision. 
One or two smaller varieties of lizards are, with the exception of birds, the bat above mentioned, and 
a species of frog, the only other land vertebrates existent within the area. 

Indigenous birds are at the present time apparently less numerous in the Coromandel subdivision 
than in former years. Members of the Geological Survey party, whose work was principallv confined 
to the watercourses in the deeper recesses of the bush, were frequently forced to remark on the still- 
ness of the forest and the general absence of bird-life. Excursions, however, to the higher countrv, 
the crests of the mountains and ridges, partly dispelled this impression. 

The larger of the birds of flight met with in the forest are the pigeon or kereru (Carpophaga nova>- 
zealandia?), the kaka (Nestor meridionalis), the parson-bird or tui (Prosthemadera novcr-zealandicr), 
the morepork or New Zealand owl (Ninox novo?-zealandia?), and less frequently the makomako or 
bell-bird (Anthornis melanura). 

Among the smaller species, the black and pied fantails (Rhipidura fuliginosa, R. flabellifera). the 
silver-eye or blight-bird (Zosterops cwrulescens), and the tomtit (Petrwca toitoi) are common ; while 
the long-tailed New Zealand cuckoo or koekoea (Urodynamis laitensis) is also seen from November to 
the end of January. 

The interesting flightless birds of New Zealand are here represented by the North Island 
woodhen or weka (Ocydromus greyi) and the brown kiwi (Apteryxbulleri). The former, which inhabits 
the forest and the clearings fringing the forest, is much less numerous and more timid than the South 
Island species (Ocydromus australis). The curious and characteristic call of the kiwi is seldom heard, 
and this bird is evidently fast becoming extinct in the area. 

In the lowlands and swamps the pukeko or swamp-hen (Porphyrio melanonotus) is occasionally 
seen, and also the hawk (Nesierax australis), while the lagoons and lower reaches of the 
streams are the haunts of the grey duck (Anas superciliosa), the brown duck (Anas [Elasmonetta] 
chlorotis), the teal (Fuligula novw-zealandia?), the cormorant or shag (Phalacrocorax varius), and the 
kingfisher (Halcyon vagans). 

On the coast-line abounds the variety of gulls, snipe, sandpipers, &c, common to this part of New 
Zea and. 

Insect-life is fairly abundant, including various varieties of flies, moths, butterflies, ants, cater- 
pillars, centipedes, spiders, &c. The mosquitoes and sandflies are the greatest pests in this category, 
but most dreaded is a small though comparatively rare spider, the katipo (Latrodectus katipo), whose 
bite is decidedly poisonous, and may even occasionally prove fatal. 



Amphibians arc represented by the rare New Zealand frog (Liopelma hochstetteri), which is found 
in very few other localities in the colony. This animal, though by no means common, has been found 
from time to time in the vicinity of Te Moehau Mountain. 

Native fresh-water fishes are limited to eels (Anguilla auslralis, A. aucMandi), Maori trout or kokopu 
(dalaxias jasciatus), crustaceans in the shape of a small crayfish (Para nephrons), and a variety of 
sluimp. The marine fish characteristic of the northern part of New Zealand are abundant, and some 
of the more important will be mentioned in connection with the fishing industry. 

Introduced mammalian life includes, in addition to the ordinary farm and domestic animals, 
rabbits, weasels, rats, and mice. The wild bush-pigs, the flesh of which affords a welcome addition to 
the food-supply of the bushman, are the progeny of animals which escaped from the settlements, and 
in part, it is said, of animals liberated by Captain Cook's party, which landed at Mercury Bay in 1769. 
Goats and cattle are in certain localities found running wild in the more remote parts of the forest. 

The various birds which have been acclimatised, and are now common to the greater part of New 
Zealand, exist here. Among these may be mentioned the pheasant (Phasianus colchious) and the Cali- 
fornian quail (CaUipepla califomica), both imported for game, also the well-known small birds — 
sparrow (Passer domesticus), thrush (Turdus musicus), lark [Alauda arvensis), blackbird (Turdus mania), 
goldfinch (Carduelis elegans), yellow-hammer (Emberiza cUrinetta), starling (Sturnus vulgaris). 

The most suitable streams of the Coromandel area have within the last few years been stocked 
with the rainbow trout. In the small tributaries ol the Mahakirau River, and to a lesser extent in the 
main river itself, these fish, varying up to 7 in. in length, are to be seen. The efforts of the Acclima- 
tisation Society therefore promise to lie rewarded within a few years by the trout-fishing which this 
fine stream should afford. 

Flora.* 

The Cape Colville Peninsula, as might be inferred from its physiographic features, mild climate, 
ami abundant rainfall, affords conditions particularly favourable for the growth of forest vegetation. 
As a result of this, the plant life is luxuriant, and in point of variety the forest compares favourably 
with that of any other part of New Zealand. 

Within the Coromandel subdivision considerable areas have, of course, been deforested for the 

purpose of settlement and cultivation, while all the accessible portions of the remaining bush have 
("■•■ii depleted of their marketable timber. The felling and removal of the kauri-pine (A</<il/n.s australis), 
a valuable building-timber which formerly grew in great abundance, necessitated partial cutting and 
clearing of much of the forest. The timber-getter was usually followed by the kauri-gum digger, who 
sometimes resorted to further clearing and even to burning in order to facilitate his operations. After 
the lapse of a few years the areas partially deprived of their primeval growth become covered with 

a dense and almost impenetrable secondary growth, which is the bane of the mining prospector and 
the backwoodsman. Only in the less accessible portions of the area is the forest found in its virgin 
condition. 

A gradual change iii the character of the vegetation is noticeable to an observer as he ascends 
from the coastline to the summits of the higher ranges. 

On the actual coast-line the muddy flats of the sheltered inlets are being reclaimed by the growth 
of Avicermia officinalis (mangrove), while the inner portions of the sand-dunes of the exposed coast- 
lines are frequently bound by Scirpus frondosus, Carex pumila, Spinifex, and Convolvulus soldanella. 
The rocky portions of the coast-line are the habitat of Mclrosideros tomrntosa (pohutukawa), which, 
however, also grows on the sandy beaches. With this tree, in the former localities, occur Pittosporum 
crassijolium, Coprosma baueri, and Astelia banksii, while Sicyos angulatus and Bidens pilosa are less 
often seen. Near the sandy beaches Isolepis nodosa and Calystegia soldanella are usually common. 
The pohutukawa frequently grows with a considerable portion of its trunk bent over and touching 
the ground, and is particularly conspicuous during the summer months owing to the abundance of its 
brilliant scarlet blooms. 



* The writers are indebted to Mr. T. F. Cheeseman, the author of ' Manual of New Zealand Flora," for informa- 
tion relating to the flora of the subdivision. 



6 

It is interesting to note that Fuchsia procumbens, Veronica pubescent;, and Pisonia brunomona, 
seen in a few places along the coast, are rare plants which were collected by the first botanists in New 
Zealand. 

In the swamp ground the most common plants are Drosera birtata, Haloragis micrantha, Hydro- 
ootyle asiatica, Lobelia anceps, Juncus planifolius, Typha angustifolia (raupo), Sparganium simplex, 
Cyperus ustulatus, Eleocharis acuta. Cladium glomeratum. 

The New Zealand flax (Phormium tenax) grows on the rich swamp ground and on the banks of 
streams ; the allied species P. cookianum, easily recognised by its smaller size and long twisted capsules, 
occurs in places on the shore-line and on the low ridges. 

The small areas of level ground at the heads of the various bays, and the alluvial flats by the sides 
of the streams, often support dense clumps of Leptospermum ericoides and L. scoparium (manuka, or 
tea-tree), the trunks of which often exceed 10 in. in diameter ; as a second growth over the whole, of 
the exposed country at low elevations, stunted manuka and Pteris esculenta (bracken-fern) are of com- 
mon occurrence. 

The most heavily bushed zone extends from near sea-level to an elevation of about 1,200 ft. The 
predominant forest-trees are El&ocarpm dentatus (hinau). Dodonrea viscosa (akeake), Corynocarpus 
laevigata (karaka), Sophora tetraptera (kowhai), Weinmannia sylvicola (tawhero), Metrosidero's robusta 
(rata), Vitex lucens (puriri), Laurelia novo?-zealandice (pukatea), Beitschmiedia tava (tawa), Beilschmiedia 
tarairi (taraire), Knightia excelsa (rewarewa), Agathis australis (kauri), Podocarpus totara (totara), 
Podocarpus ferrugineus (iniro), Podocarpus spicatus (matai, or black-pine), Podocarpus dacrydioides 
(kahikatea), Dacrydium cupressinum (rirnu), I). intermedium. 

Agathis australis (kauri-pine), the most gigantic of the New Zealand forest-trees, was formerly 
abundant in this area, but now only exists as isolated trees or small clumps in the more inaccessible 
localities. 

The chief plants associated with the above or constituting the undergrowth are clematis, Melicytus 
ramiflorus (niahoe), Hoheria populnea (houhere), Aristotelia racemosa (makomako), Dysoxylum spectabile 
(kohekohe), Pomaderris, Coriaria ruscifolia (tutu), Rubus australis (tataramoa, or bush-lawyer), 
Myrtus bnllata, Fuchsia excorticata (kotukutuku), Pseudopanax crassifolium (horoeka, or lancewood), 
Griselinia lucida (puka), Coprosma robusta (karamu), Olearia cunninghamii, Brachyglottis repanda 
(pukapuka), Dracophyttum latifolium (neinei), Veronica salicifolia (koromiko), Hedycarya arborea 
(porokaiwhiri), Rhipogonum scandens (supplejack), Cordyline australis (ti), Astelia solandri, Areca sapida 
(nikau), Freycinetia banksii (kiekie), Cyathea dealbata (ponga), Pteris scaberula, Lygodium articulatum 
(mangemange), Lycopodium volubile* 

On the crests of the higher ranges the vegetation assumes a different character, and on the summit 
of the main range south of Te Moehau Mountain the following forms are to be observed : Drimys 
axillaris, Melicytus macrophyllus, M. lanceolatus, Elmocarpus hoolcerianus, Quintinia serrata, Ixerba 
brexioides, Weinmannia sylvicola, Metrosideros lucida, Myrtus bullata, Fuchsia excorticata, Aleuosmia 
macrophylla, Coprosma lucida, C. fcetidissima, Senecio kirkii, S. myrianthos, Dracophyttum latifolium, 
Rhipogonum scandens, Astelia grandis, A. trinervia, Pteris incisa, and Polypodium rugulosum. The 
largest trees here are Weinmannia sylvicola (tawhero), and Laurelia novce-zealandia? (pukatea). 

The peak of Te Moehau (2,935 ft.) is comparatively bare, and is of considerable interest from a 
botanical point of view, in that it supports a true subalpine vegetation. " Some of the plants found 
here," remarks Mr. James Adams,f who investigated the flora of the mountain, " are not found nearer 
than the top of Hikurangi in the Ruahine Range — viz., Celmisia incana, Pentachondra pumila, Ourisia 
macrophylla, Dacrydium bidwittii, Podocarpus nivalis, Danthonia semiannularis var. alpina, Oreobolus 
pumilio, Carpha alpina, Gleichenia dicarpa var. alpina." 

Te Aroha Mountain (3,128 ft.), which consists of volcanic rocks, and occurs in the southern por- 
tion <-f the Hauraki Division, though it is 193 ft. higher than Te Moehau, shows none of these plants. 
But it occupies a more sheltered position, and it has not the broad wind-swept summit of Te Moehau. 
Hence the forest extends to the very top, and there is no open ground suitable for the growth of small 



* The genera are arranged according to the sequence in Cheeseman's "Manual of New Zealand Flora." 
t Trans N.Z Inst. vol. xxi. 1888, p. 40. 



mountain plants. In this connection it is worthy of note that Mr. Adams remarks that the botanical 
evidence " appears to prove that Moehau is the oldest land-formation on the Cape Colville Penin- 
sula."* 

Climate. 

The climate of the Coromandel subdivision offers no marked divergence from that prevailing 
in similar forest-clad localities in the northern portion of the Auckland Land District. Since there is 
no meteorological station within the subdivision, actual statistics as to temperature, rainfall, &c, cannot 
he given. The rainfall may be approximately gauged from records taken at the nearest stations — 
namely, Auckland City, Turua, Waihi, and Katikati. 

lis will be seen by reference to Chapter IV, the area under review forms the northern portion of 
general meridional-trending peninsula, with an axial divide averaging l,f>00ft. in elevation. The 
meteorological stations Waihi and Katikati. lie on the southern continuation of the peninsula, 44 miles 
and 55 miles respectively south of the latitude of Coromandel Township, and on the eastern side of the 
divide ; Turua lies on the low ground of the mainland. 34 miles south of Coromandel and S miles to the 
west of of its peninsular divide. Auckland City, situated on the mainland in country of low elevation, 
lies 40 miles to the west of Coromandel. and on the opposite shore of the Hauraki (Julf. 

Records quoted as taken at Waihi. Katikati. and Turua. are the results of observations extend- 
ing over a period of six years, ending the 31st December, 190C>. The returns for Auckland are averages 
for forty years. The tabulations show the mean rainfall in inches per month, and also the mean number 
of days on which rain fell in each month. 



Jan. 



Feb. March. April. May. June. July Aug. Sept. 



Oct. 



\ . i v 



Dee. 



I "t.'ll.H. 



\lKVS K IINKU I EH I\( ItKS. 



Waihi 

Katikati 

Turua 

Auckland 



Waihi 
Katikati 
Turua 
Auckland . . 



8-24 


i -58 


4-30 


2-89 



Hi.". 
4-80 
3-4S 
3-50 



7-73 
6-32 

3-33 
t ••_'•.' 



Mkvn Ximhkk of Days with BUnr. 



B-42 


5*70 


7 -is 


7-38 


s-sl 


t-io 


it:. 


6-38 


t:»7 


7-fiO 


314 


1-61 


3-<;i 


3-56 


616 


.'•:u 


3-15 


i-ji 


4-7!i 


i 86 



S-ll 


7-87 


*-39 


•"> 1 7 


5 10 


.v:{ I 


41 1 


3-66 


1-68 


5*30 


.1-1 s 


3-29 


3*39 




3 -_!3 


2-64 



80-28 
61-97 
18-63 

42-36 



10 
13 
II 
10 



II 


1 1 


16 


17 


17 


IS 


17 


17 


18 


13£ 


13 


11 


11 


14 


16 


16 


IK 


16 


L8 


17 


16 


12 


9 


9 


13 


14 


1 t 


i:»A 


in 


17 


13 


10i 


13 


10 


g 


12 


1 1 


18 


19 


17 


16 


16 


12 


11 



176 
166 

103 



These figures show a considerable variation in the mean rainfall at the several stations, and this is 
probably referable to local configuration. The rainfall recorded at Turua. of all these meteorological 
stations, may be assumed to most nearly approximate that of Coromandel Township. 

The winds from the east and north-east are those accompanied by the heavy rains. The winds 
from the westerly direction are accompanied l>v fine weather, while those from the south- easl generally 
result in cold weather with at times heavy showers. The general humidity of the climate is also 
evidenced by heavy dews which fall between sunset and sunrise. 

Snow seldom or never falls in the subdivision, excepting on the crest of the mountain divide in the 
vicinity of Te Moehau Mountain, where the elevation ranges from 2.500 ft. to 2,935 ft. Even in this 
particular locality only very light falls occur in the most severe winter seasons. 

As regards temperature, no records have heen taken, except at the major station at Auckland 
City. These returns for a period extending over forty vears show that the mean annual temperature 
is 588° F., that the coldest month is July, mean temperature ")2 - l° F., and the hottest month January, 
mean temperature 67"1° F., hence there is a remarkably slight variation in the mean temperature of 
the hottest and coldest months. It is believed that the extremes at Coromandel are somewhat greater 
than those at Auckland City. 



Trans. X.Z. Inst., vol. \xi. 1888, p. 1" 



Scenery. 

The Hauraki Peninsula, and more particularly the northern portion of the Coromandel area, has 
long been noted for its scenic beauty. From consideration of latitude and general elevation, one does 
not here look for the grandeur of the scenery and the magnitude of the land-forms which characterize 
much of the South Island country. The scenery of the Coromandel subdivision, however, possesses 
a charm of its own in the wonderful blending of the seascape with mountain and forest. The view 
from any of the main vantage-points on a clear day is one not soon to be forgotten, and a brief descrip- 
tion based upon notes taken on an ascent of Te Moehau Peak may be here submitted. 

Te Moehau (2,935 ft.), the highest mountain in the area, lies in the northern prolongation, some 
sixteen miles, as the crow flies, from Coromandel, the main centre of population, and is not particularly 
easy of access, but the magnificent view obtained from its summit, if the weather-conditions are favour- 
able, amply repays the climber. This view is probably unsurpassed for range and quality by that 
obtained from any other point within a similar distance of Auckland City. The whole of the broken 
eastern coast-line of the North Island, with its background of undulating and mountainous country 
extending from Whangarei Heads in the north to the shores of the Bay of Plenty in the south, is spread 
out before the gaze of the spectator. To the west Auckland City facing the waters of the Waitemata 
Harbour, and the numerous volcanic cones studding the isthmus upon which the city stands are 
plainly visible, with the upper reaches of the Manukau Harbour, a deep indentation of the western 
coast-line of the North Island, in the background. The numerous rock-girt islands of the Hauraki 
Gulf, more particularly those which skirt the coast-line of the Cape Colville Peninsula from Te 
Kouma Harbour to Cabbage Bay, are especially picturesque. These islands all rise to considerable 
elevations above the sea-level, and are in the main covered with vegetation. To the north of Cape 
Colville the Great and Little Barrier Islands, and to the east Cuvier, Mercury, and a few smaller- 
islands alone break the broad expanse of the Pacific Ocean. 

The view of the peninsula itself looking southward from Te Moehau Mountain reveals strikingly the 
general rugged and broken character of the land- mass from coast-line to coast-line and the small pro- 
portion that the patches of low-lying country bear to the total area. Hill rising beyond hill, and ridge 
beyond ridge, appear as far as the eye can see. The Castle Rock and some of the other landmarks 
of the main range are not conspicuous against this background of hills, but the Camelback, the flat- 
topped Table Mountain, and Mount Te Aroha stand out clearly. It is, however, the nearer view that 
gives much of the charm to the scene. The luxuriant forest vegetation, with its every shade of green 
relieved in summer by the scarlet blooms of the rata, and near the coast-line by the brilliant flowers 
of the pohutukawa, clothes ridge and valley alike down to the very water's edge. Bays and harbours, 
a^ording sheltered sheets of water, indent the rock-girt coast-line, while the lighter-green colour of the 
cultivated fields near their margins contrasts strongly with the more sombre tints of the forest. Away 
in the direction of the Kuaotunu Peninsula the long white shelly beaches of this exposed coast-line, 
broken here and there by rocky headlands jutting out into the ocean, are bright and conspicuous on a 
fine day. 

Although Te Moehau commands by far the most extensive view of the northern peninsular heights, 
Te Ranga (Look-out Rock), Tokatea Hill, Kaipawa, Castle Rock, and Pukewhakataratara, major 
elevations on the main range and all easily accessible, are vantage-points which afford particularly 
charming views of the surrounding country. 

A ride along one of the many bush roads or tracks reveals the great wealth of the flora. Where 
the heavier trees have escaped the onslaught of the timber-cutter and the ravages of the forest-fires, 
the gigantic kauri (the "monarch of the New Zealand forest"), the rimu, the totara, and the kahi- 
katea, tower above a luxuriant vegetation. The stately nikau palm, the gorgeous tree-ferns, and the 
handsome creepers here lend a semi-tropical aspect to the forest. 

The picturesque gorges, cascades, and waterfalls, and the many rushing streams traversing this 
densely forested country, are in the main revealed only to those who penetrate into the deeper recesses 
of the woodlands. 



PLATK I. 




Castle Rock, frou the Waiau Valley. 

[Photo, by Mr. [lex. McKay, F.G.S. 




Castle Rock, fhom the South-west. 

[Photo, by Mr. Alex. McKay, F.G.S. 



Geo. Bull. No. ',.] 



[To face p. 8. 



9 

Literature. 

Since the date of the earliest gold-discoveries many reports and notices have appeared, dealing 
with the geology and the mining industry of the area included within the Coromandel subdivision. The 

following list of authors and their publications may be considered fairly complete : — 
The abbreviations used are — 

Q.J.G.S. : Quarterly Journal of Geological Society, London. 
Trans. : Transactions of the Xew Zealand Institute. 
Rep. G.S. . Reports of the Geological Survey of Xew Zealand. 

A capital letter followed by a figure (thus : C.-3) refers to a New Zealand parliamentary 
paper. 

1854. Efeaphy, Charles: "'The Coromandel Gold-diggings." Q.J.G.S., vol. x. p. 322. 

This is a short contribution describing the methods used to recover the detrita] gold and 
auriferous quartz from the creek-gravels, and indicates a course for future operations. 

1855. Heaphy, Charles: " The Gold-bearing District of Coromandel Harbour." Q.J.G.S., vol. xi, p. 31. 

This contribution i^ive-. an outline of the jj^ologv of the locality, with special reference 
to the auriferous occurrences. 

1864. Hochstetter, Ferd. von : "The Geology ol New Zealand, in Explanation of the Geological and 
Topographical Atlas of Xew Zealand." (Translated by Dr. C. F. Fischer. Auckland.) 
Hochstetter. Kerd. von. and I'etei maim. A. : "The Geology of New Zealand." 

Pp. 15 and .")| have reference to the gold found at Coromandel. 
Hochstetter, Ferd. von: " Geologic von Neu-Seeland Beitrage zur Geologie der Provinzen 
Auckland und Nelson." " Novara " Exp., Geolog. Theil, Erster Hand. Erste Abtheilung. 

1867. Hochstetter, Ferd. von " NVw Zealand, its Physical Geography, Geology, and Natural History." 
(Stuttgart, J. G. Cotta.) 

l'p. '.»! 98 give a Bhorl geological and historical account ol the Coromandel Goldfield. 

1869. Hector, -lane'- : " Bfining in New Zealand." (Abstract of Lectures delivered at the Colonial 

Museum.) Trans., vol. ii, p. .'561. 

I'p- ■" ,, i" 68 have brief reference to [nining at Coromandel. 

1870. Hutton, F W. : "TheGeologj ol Coromandel." Rep! G.S., 1870 71. pp. 2 5. 

This Is a -hurt report on tie' : ... and has reference to the existing mining 

areas. 

Hector, Jane-: "The Geology ot (ape Colville District." Rep. G.8., 1^70 71. 

Pp. 88-9S have reference to the geology of the Coromandel district and the earliest mining 
operations. 

1881. Cox, s. H. : "North [aland District, including Thames, Coromandel, Island ol Kawau, and 

Driirv Coaltields." Rep. G.S., 1881. 

Pp. 40-41 refer to the rocks of Tokatea Hill, and small coal-seams in the vicinity of Cab- 
bage Bay. 
Cox, S. H. : "Notes on the Mineralogy of New Zealand," Trans., vol. \iv, pp. 418-50. 

This report describes certain minerals occurring a1 Coromandel. 
Cox, S. H. : "Goldfields of Cap.- Colville Peninsula." Hep. C.S., pp. 4 51. 

This report deals with the geology of the peninsula as a whole, excepting the Mercury 
Bay area. 
Cox, S. H. : "Notes on the Mineralogy ol New Zealand." Trans., vol. xv, p. 361. 

Continuation of paper of 1881. This describes the non-metallic minerals and cites various 
occurrences in the Coromandel subdivision. 

1883. Bramhall, H. : " The Mineral Resources of New Zealand." Trans. Liverpool Geol. Ass. 

McKay, A.: "The Geology o! Cabbage Bay District, Cape Colville Peninsula." Rep. G.S., 
1885, ]». 192. 

This report has special reference to the coal-bearing rocks near Torehine. 



10 

1887. Pond, J. A. : " Minerals of Cape Colville Peninsula." C.-3, p. 56. 

Contains references to minerals occurring in the Cororaandel subdivision. 
Galvin, P. : " Handbook of New Zealand Mines." (Preface by Hon. W. J. M. Larnach.) 

This volume has references to mining on the Coromandel Goldfield, pp. 278, 291, 295-99. 
Button, F. W. : " The Rocks of the Hauraki Goldfields." Anst. Ass. Adv. Science, vol. i, 
p. 245. 

This contribution deals with the volcanic rocks in which the auriferous veins occur. 
Skey, William and McKay. A. : " Gold : Its Formation in our Reefs ; and Notes of some Newly 
Discovered Reactions." Aust. Ass. Adv. Science, vol i, p. 155. 

1889. Hutton, F. W. : " The Eruptive Rocks of New Zealand." Journ. Royal Soc. of N.S.W., vol. xxiii, 

p. 102. 

P. 128, hornblende porphyrito. p. 133, hornblende andesite, from Cororaandel, are petro 
graphically described. 

1890. C.-3, p. 39. 

This contains the first official reference to the Kuaotunu Goldfield. 
Hector, James : " Minerals of New Zealand." Rep. G.S., 1892, p. 105. 
This mentions many minerals from the Coromandel subdivision. 

1893. Park. James : " Notes on the Geology of the Kuaotunu Goldfield." Trans., vol. xxvi, p. 360. 

1894. Murray, R. A. F. : " Report on Deep Quartz Mining in New Zealand." C.-6. 

Pp. 1-5 have reference to mining conditions at Coromandel. 

1895. Cadell, H. M. : " Gold-mining in the Hauraki District, New Zealand." Trans. Fed. Inst. Min. 

Eng. 

Extracts from this paper are published in C.-3, 1896, p. 81. 

1897. Park, James : " The Geology and Veins of the Hauraki Goldfields, New Zealand, with Maps and 

Sections." Trans. N.Z. Inst. Min. Eng. 

This concise report includes a description of the geology of the Coromandel subdivision, 
and makes special reference to the several mining centres. 
McKay, A. : " Geology of the Cape Colville Peninsula, with Map." C.-3, 1897. 

This report covers the geology of the whole peninsula, with lengthy extracts from former 
writers on special areas. 
McKay, A. : " Thermal Springs and Sinter-deposits of Cape Colville Peninsula." C.-9, p. 71. 

Contains many references to occurrences in the Coromandel subdivision. 
Campbell, Joseph : " The Goldfields of the Hauraki Peninsula." Trans. Fed. Inst. Min. Eng.. 

pp. 12, 462, 482. 
Campbell, Joseph : " Volcanic Zone of the Hauraki Goldfields." Scottish Geol. Mag., p. 246. 
Wauchope, J. A. : " The Goldfields of the Hauraki District," Trans. Fed. Inst. Min. Eng., 
vol. xiv, pp. 19, 45. 

1898. Don, J. R. : " The Genesis of certain Auriferous Lodes." Trans. Am. Inst. Min. Eng., vol. xxvii. 
Maclaren, J. M. : " The Occurrence of Gold in the Coromandel District." Trans., vol. xxxi, p. 492. 

This contribution describes the occurrence of gold in a crystalline form from Tokatea 

Hill. 
Maclaren, J. M. : " The Geology of Te Moehau." Trans., vol. xxxi, p. 494. 
McLeod, W. A. : " Notes on a Hornblende Trachyte from Tawhetarangi." Trans., vol. xxxi, 

p. 490. 
Wilson, Geo. : " On some Differences that distinguish the Goldfields of the Hauraki Mining 

District, New Zealand." N.Z. Inst. Min. Eng., vol. ii, p. 17. 

1899. Maclaren, J. M. : " Castle Rock, Coromandel." Trans., vol. xxxii, p. 213. 

This contribution describes the geological and topographical features of Castle Rock. 
Park, J., and Rutley, F. : " Notes on the Rhyolites of the Hauraki Goldfields, New Zealand." 
Q.J.G.S., vol. iv, p. 449. 

This contains a petrographical description of a rhyolite from Mercury Bay. 



11 

1900. Park. James : " Notes on the Geological Examination of the Hauraki Goldfields." New Zea- 

land Mines Record, vol. iii, p. 376. 
Maclaren, J. M. : " The Geology of the Coromandel Goldfield." C-9, 1900. 

This is a detailed geological report on the Coromandel Goldfield, with maps and sections. 

1901. Mulgan, E. K. : " The Volcanic Grits and Ash-beds in the Waitemata Series." Trans., vol. xxxiv, 

p. 414. 

This paper has an indirect bearing on the geology of the Coromandel subdivision, in that 
it suggests a Miocene age for the volcanic rocks of the Beeson's Island Series. 
Allen, F. B. : "Tellurium in the Ores of the Hauraki Goldfields." New Zealand Mines Record, 
vol. iv, pp. 467-70. 

Coromandel is reported as the locality of one of the occurrences. 

1903. Park, I. : " On the Jurassic Age of the Maitai Series." Trans., vol. xxxvi, p. 44-i. 

In reviewing certain areas of so-called Maitai rocks, the writer ascribes an age no greater 
than Juro-Triassic to the basement rocks of the Hauraki Peninsula. 

1904. McKay, A.: "The Igneous Character of the Carboniferous Rocks of t he Tokatea Goldfield, 

Cape Colville Peninsula." C.-3, pp. 6-9. 

1905. McKay, A., and Sollas, W. J. : " Rocks of the Cape Colville Peninsula." 1905-6 (two volumes). 

This is the most complete and voluminous report yet issued on the petrography of the 
whole peninsula. It also covers briefly the general geology of the area, and includes pertinent 
field-notes. 
Marshall, P. : " The Geography of New Zealand." (Publishers, Whitcombe and Tombs, Wel- 
lington, N.Z.) 

This volume contains brief reference to the physiographic features of the Cape Colville 
Peninsula. 

1906. Galvin. P. : " The Mining Handbook of New Zealand." 

Eaa reference to the Coromandel subdivision in several articles, pp. 4, 17, 39, and 52. 
Park, J. : "' A Text-book of Mining Geology." (Publishers, Macmillan and Co.) 

In this volume many of the illustrative examples are drawn from vein-occurrences in 
the mining centres of the Hauraki goldfield-. 
I.oughnan, R. A. : " The First Qold-disooveries in New Zealand." (Wellington, Government 
Printer.) Reprint from New Zeal-and Aftnas Record, vols. ix and x. 



12 



CHAPTER II. 



GENERAL CULTURE. 



Towns and Settlements . . 

Means of Communication 

History of Gold-mining in the Coromandel 
Subdivision . . 

Mineral-production 

Industries other than Mining and Quarry- 
ing 



'age 










Page 


12 


Industries other 


than 


.Mining and 


Quarry 




13 


ing — contini 
Agriculture . 


ed. 






Hi 


14 


Timber 








20 


18 


Kauri-gum 
Flax 








20 
21 


lit 


Fishing 








21 



Towns and Settlements. 

The earliest European settlements on the Cape Colville Peninsula depended for their existence 
upon the kauri-timber industry. The western side of the peninsula, with its shores washed bv the 
sheltered waters of the Hauraki Gulf and Firth of Thames, possessed special advantages in this connec- 
tion ; the forests extended almost to the water's edge, and contained a plentiful supply of kauri ; the 
various sheltered inlets rendered most of the forest easily accessible ; the rising seaport town of Auck- 
land, distant only some forty miles on the opposite shore of the gulf, afforded a ready market for the 
building-material. Coromandel, Cabbage Bay, and Manaia were among the earliest of the west-coast 
settlements within the boundaries of the subdivision. On the eastern side of the peninsula the kauri 
forests of Mercury Bay, Whangapoua, Kennedy s Bay, and Port Charles, also attracted attention at 
an early date, and settlements dependent on the timber industry sprang up in these localities. 

On account of the limited area of country covered by kauri and other sawmilling timbers, only 
those settlements that had natural resources other than timber had any real permanence. It is to 
gold-mining and to agricultural and pastoral pursuits that almost all the present settlements owe their 
existence. The working of the remnants of the kauri forests, and the digging of kauri-gum, however, 
still afford the means of livelihood to a limited number of the population. 

The township of Coromandel is named after a British man-of-war which, in 1820, put into the 
harbour for the purpose of obtaining spars (kauri) for the navy. Some considerable time after this 
date the low grounds of the valley became the scene of active sawmilling operations, and thus a 
European settlement came into existence. Coromandel, however, if dependent solely on its timber 
resources, would, ike many another such sawmilling centre, have rapidly declined. Ring's discovery 
in 1852 of fragments of highly auriferous quartz and detrital gold in a creek-bed threw quite a new 
light on the future prospects of the district. There was an immediate influx of a class of pioneers very 
different from the bushmen — namely, the gold-diggers and those who invariably follow in their 
wake. Even at that early date the possibilities of Coromandel as a goldfie'd were hopefully discussed, 
and subsequent discoveries were sufficient to estab ish it as a permanent mining centre. 

The present township is charmingly situated on the ow grounds of the valley between the foothills 
of the range and a picturesque harbour. Its history, owing to its dependence mainly on auriferous 
veins of the bonanza type, records several mining excitements, and attendant periods of prosperity, 
followed by the inevitable periods of depression. 

According to the census of 1906, Coromandel contained a population of 1,208, although only eight 
years previously, owing to the mining " boom " in progress at that time, the population totalled over 
three thousand. 

Cabbage Bay, situated some nine miles in a straight line north of Coromandel, according to the census 
of 1906 had a population of 108. The settlement was formerly the scene of active sawmilling opera- 
tions, but, as only remnants of these kauri forests now exist, agriculture, kauri^gum digging, and occasion- 
ally mining and gold-prospecting operations, give employment to its limited population. 



13 

Manaia is a settlement some five and a half miles, as the crow flies, to the south of Coromandel, 
situated on the low alluvial flat at the mouth of the Manaia Stream, which enters the harbour of the 
same name. The population at the present time consists almost entirely of Maoris, but was 
formerly supplemented by Europeans engaged in the gold-mining and kauri-timber industries. The 
Maoris now eke out an existence by the tilling of the soil and by fishing. 

Whitianga, situated on the estuary of the same name opening into Mercury Bay. is a small but 
flourishing seaport with a population of -170, which owes its existence not to mining, but to the milling 
and exporting of kauri timber, and to agriculture. It also forms the port for the smaller settlements 
situated in the valleys of the streams which flow into the estuary. 

Kuaotunu is a straggling settlement lying in the val'ey of the Kuaotunu Stream, on the northern 
side of the peninsula of the same name. It was formerly a nourishing mining cam}), with a population 
of about 800, which has gradua"y decreased until by the census of 1906 it stood at 281. Mining, 
agriculture, and kauri-gum digging afford its inhabitants the means of livelihood. 

Whangapoua (population 73), Kennedy's Bay (population 51), Port Charles (population 34), are all 
located in more or less sheltered coastal inlets, and the inhabitants arc supported mainly by agri- 
cultural and pastoral pursuits, timber-cutting, kauri-gum digging, and flax-milling. 

The population, exclusive of Maoris, of the Coromandel County, according to the census of 
1906, was 2,841, and of this number some L',620 resided within the area, included in the Coromandel 
subdivision. The Maoris scattered through the small coastal settlements number in all some 695, a 
mere remnant of the several powerful tribes that once peopled this portion of the peninsula. 

Means ok Commtjnk mion. 

No factor is more important in the exploitation and development of a goldfie'd than adequate and 
ready means of communication. In this connection the Coromandel subdivision, owing to its peninsular 
form and its proximity to Auckland the provincial metropolis, is very favourably situated. 

Harbours, Ac. The picturesque harbour which gives access to Coromandel, the principal settle- 
ment, is almost landlocked, and consequently well sheltered. The principal disadvantage is due to the 
continual deposit of fine rock debris from various stream-, which is effecting a gradual silting-up along 
the inner part of its margin. The wharf accommodation, owing to this shallowness of the water, is 
available, even for light-draught vessels, only at favourable states of the fide. Small steamers, how- 
ever, which are capable of making the trip m less than four hours, trade regularly bet ween this port 
and Auckland. 

Communication with the other settlements on inlet- of the western coast-line -Cabbage Bay and 
Manaia — is Bubjecl to the same disadvantage, extensive mud-flats extending along the shore-line ( >t 

their harbours at low tide. Small steamers furnish means of communication with Coromandel. 

On the more exposed eastern coast-line of the peninsula, Porl < lharles, Kennedy's Bay, and Whanga- 
poua afford -ome shelter lor coastal shipping ; hut the latter is a bar-harbour, and is workable only 

in very favourable weather. Kuaotunu is hounded by an exposed beach, and the coastal steamers 
can he tendered by barges and surf-boat- only at favourable opportunities. Whitianga is much 

more happily situated. Bines the deep estuary which enters Mercury Bay furnishes sale anchorage for 
even the large ocean-going barques which are engaged in the kauri-timber export trade. 

Regularly trading coastal steamers connect Whitianga and. during favourable weather, the 
smaller coastal settlements further north with the Port <>f Auckland. 

Roads and Trail,*. The main overland route is the coach-road of some thirty-five miles in length. 

which connects Coromandel Township with the Thames, a more populous mining centre, and the 
railway terminus of the southern portion of the peninsula. Leaving Coromandeh this well graded 
and metalled road, after traversing the low grounds of the Tiki and passing over the hilly country 
separating the Coromandel and Manaia Harbours, reaches the Maori settlement of Manaia. From the 
alluvial flats of this settlement the road passes across the hilly country between Manaia and Kirita Bay, 
attaining a maximum elevation of 680 ft., and striking again lor the coast-line it passesfbeyond the 
boundary of the Coromandel subdivision. 

Graded bridle-tracks, as indicated on the maps accompanying this bulletin, connect Cabbage 



14 

Bay, Waiaro, and other minor settlements of the north-western coast-line, with the Township of Coro- 
mandel. Between Waiaro and Port Jackson a partly formed track exists. 

In regard to overland communication between the settlements of the eastern and western shores 
of the peninsula, the mountain divide, which preserves an average elevation of about 1,500 ft., has 
always constituted the main engineering difficulty. Added- to this is the fact that stone suitable for 
roadmaking is, over certain areas, only obtainable at long intervals, owing to a very general alteration 
and decomposition of the volcanic rocks. Very fair roads and tracks, however, exist, and these are 
constantly in course of improvement or extension. The road between Coromandel and Whitianga 
has up to the present time been passable only for saddle-horses ; but the necessary improvements 
now in progress along the more elevated stretches will very shortly admit of wheeled traffic between 
these centres. 

Other cross-country graded roads and tracks radiating from the main centre of population are the 
Coromandel-Kuaotunu Road via Whangapoua, the Coromandel-Whangapoua Road via the Tiki 
Hill, and the Coromandel - Kennedy Bay Road via Tokatea Saddle. The first two of these are at present 
adapted only for saddle-horse traffic ; but the last-named, although in part of high gradient, permits 
of vehicular conveyance. Graded tracks connect Cabbage Bay on the west coast with Waikawau 
and Port Charles on the east coast, while an (old and partly overgrown foot-track exists between 
Waiaro and the latter locality. 

The various settlements of the eastern coast-line are connected with one another in part by portions 
of the routes already mentioned, and in part by specially formed roads and tracks. A graded bridle- 
track extends from Port Charles almost to Port Jackson. Port Charles is connected with Waikawau, 
and Waikawau with Kennedy's Bay. An unformed bush track leads from Kennedy's Bay to Whangapoua, 
and this latter settlement is itself connected with the main Coromandel-Kuaotunu Road. A road 
constructed for wheeled traffic leads from Kuaotunu to Whitianga, and from Whitianga formed bridle- 
tracks extend southward and south-eastward to Gumtown and Tairua, settlements located beyond 
the limits of the Coromandel subdivision. 

Numerous minor roads and tracks connect outlying and isolated mining claims with the principal 
routes already mentioned. 

Coromandel Township has telegraphic or telephonic communication with Auckland and Thames, 
and with the settlements of Whitianga, Kuaotunu, Whangapoua, and Cabbage Bay, all within the 
subdivision. 

History of Gold-mining in the Coromandel Subdivision. 

The discovery of gold in Australia in 1851, by Hargreaves, reacted very sensibly on New Zealand, 
since scarcely had the latter colony overcome the difficulties attending the commencement of its colon- 
isation when a great number of its pioneering population rushed away to the new El Dorado. 

The discoverie in Australia had, however, to some extent a beneficial effect on New Zealand, in 
that they directed attention to the possible occurrence of gold in this colony. Prospecting in New 
Zealand was therefore commenced, and received an incentive owing to the formation in Auckland, in 
October, 1852, of a Reward Committee, which offered a £500 bonus to the discoverer of a payable gold- 
field in the northern province. Within a week the bonus was claimed by Mr. Charles Ring, then a 
sawmiller in the Coromandel Valley, and, prior to arriving in New Zealand, a gold-prospector in Cali- 
fornia. Ring announced that he had discovered a payable goldfield at Coromandel, and produced at 
the same time specimens of auriferous quartz and a certain amount of fine detrital gold, which he 
had obtained from the bed of the Whangarahi Creek near the base of Tokatea Hill. Thus is re- 
corded, in October, 1852, the first authenticated gold- discovery in New Zealand. 

Forthwith negotiations were opened with the Maori landowners to permit of gold-mining on the 
H;',uraki Peninsula, and resulted in an agreement (dated the 30th', November, 1852) that the area lying 
between Cape Colville and Kauaeranga (now Shortland, Thames) should be opened for mining for a 
te*m of three years. Under this agreement the Government pledged itself to pay per annum to the 
Maoris— for less than 500 men digging, £600 ; for 500 to 1,000 men digging, £900 ; for 1,000 to 1,500 
men digging, £1,200 ; for 1,500 to 2,000 men digging, £1,500 ; and, in addition, 2s. for each miner's 



PLATE II. 




"okatka Hill, prom the South east. 

[Photo, by Mr. Ahx. McKay, F.G.S. 




East Slope of Tokatea Hill. Kennedy's Bat ix the Distani e. 

[Photo, by Mr. Alex. McKay, F.G.S. 



Geo. Bull. No. .',.] 



[To face />. I'/. 



PLATE III. 




Kvaotusu Valley, looking Xorth-east from Try Fluke Battery. 

[Photo, by Mr. Alex. McKay, F.G.S. 




Kuaotunu Valley, showing Northern Termination of Bald Spur. 

[Photo, by Mr. Alex. McKay, F.G.S. 



Geo. Bull. Xo. .£.] 



[To face p. 15. 



15 

license issued. To meet this and other expenses a tax of £1 10s. per month per man was imposed on 
the miners, with, however, exemption for the first two months. 

Within one month from the date of this agreement, three thousand men were on the Coromandel 
field, and the hitherto quiet sawmilling settlement at once assumed all the characteristics of a newly 
established mining camp. It was discovered, however, even at that early stage of mining operations 
that the auriferous areas were not continuous throughout the field, and two separate camps were esta- 
blished. One of these was that of Coolahan's Diggings, on the site of the present upper township of 
Coromandel, the other that of the Waiau Diggings, on the banks of the Waiau Stream and its tribu- 
tary the Matawai. 

The results in each case were very disappointing, and of the three thousand miners who " rushed " 
the field, it is said that only fifty took out licenses at the expiration of their two months' exemption 
period, and even these could not afford to pay the heavy monthly tax. Failure to locate payable gold, 
combined with the unfriendly attitude of the Natives, caused a general exodus of the diggers, and within 
six months the whole enterprise died out. The total value of the gold obtained during this period 
was £1,200 (the largest nugget being a cobble^of auriferous quartz measuring 1| in. in diameter, and 
valued at £10 sterling). 

The stipulated bonus was withheld from Ring, since the Auckland Reward Committee did not 
consider the futiire prospects of the field sufficiently good. 

For several years further exploitation of the field was prevented by the unfriendly attitude of the 
Natives, but in October, 1861, a second " rush " set in, as the result of the discover}' of a highly auri- 
ferous quartz vein in the Kapanga (Scotty's) area, and following this Coromandel was proclaimed a 
goldfield on the 28th June, 1862. 

The Kapanga area then became the scene of great activity, and attention was also directed to the 
previously abandoned Waiau Diggings. The Tiki Creek, a tributary of the Waiau, yielded before the 
end of the same year (1862) alluvial gold valued at £200, but, although this was mostly derived from 
detrital vein-quartz, prospecting operations failed to reveal the veins themselves. 

The outbreak of Native hosti'ities in the Waikato District, Auckland, in 1863, gave a temporary 
check to mining in the Coromandel field, nevertheless the month of July of this same year saw the 
Kapanga Mine proprietors crushing ore from the vein previously mentioned. Up to May, 1864, accord- 
ing to Sir James Hector, the Kapanga Mine "yielded 2,198 oz. of gold from 1,7061b. of quartz, and 
the remaining 100 tons from which the stone was picked yielded 400 oz. : approximate total value, 
£7,143."* "Other batteries," it is stated, "obtained 1.120 oz. from 40^tons," but it is not indicated 
from whence this ore was derived. 

Operations were vigorously prosecuted with more or less success until 1866, when the discoveries 
of quartz veins of phenomenal richness at the Thames, some thirty-five miles to the south, caused a 
" rush " which deprived Coromandel of the greater part of its mining population. At the latter centre 
the Kapanga Mine alone continued working during the early part of this period of great excitement 
in the southern area. Tn 1869-70 the mining industry in Coromandel received a fresh impetus owing 
to the discovery of a wonderfully rich quartz vein on the Tokatea Hill. From 1870 to 1878 the Tokatea 
Diggings were the scene of great activity ; the Tokatea Company, operating on this vein and another 
vein, the ' Tribute leader," discovered some three years later, paid to the shareholders[£63,625 in 
dividends without calling up anv of its capital. 

Meanwhile the introduction of English capital in 1871, for the further development of the Kapanga 
Mine which had paid large dividends to the original holders, gave greater permanence to the industry. 
Furthermore, a considerable stimulus was furnished in 1872 by the discovery of the famous Green 
Harp shoot of gold, in a vein occurring in one of the low hills (within the boundary of the present Hau- 
raki Mine) skirting the north-eastern inner shore-line of the Coromandel Harbour. This in a very 
short space of time yielded gold to the value of'over £40,000. 

In respect to the few years immediately preceding 1885 there is nothing of note to record as regards 
new discoveries, and unfortunately only a graduallv diminishing output in the case of the older 



* R<|>. <;..S., vol. vi, 1871. p. 90. 



16 

claims. This year, however, saw a mild " rush " to the Tiki, as the result of the discovery 
by H. Blackmore of a rich ore-shoot in a vein, occurring in the range beyond Tiki Hill saddle. 
Vigorous prospecting in this locality resulted only in the further discovery of several very rich 
but rather small "pockets" of bonanza ore, and the Tiki Hill camp had therefore a comparatively 
short life. 

From the opening of the Coromandel field up to the year 1889, all the gold-discoveries of any im- 
portance in the area under review were confined to the watershed draining into the Coromandel Har- 
bour, and that draining into Kennedy's Bay on the eastern and opposite side of the main divide. 
Furthermore, the pay-ore was confined to rich shoots somewhat limited in extent, occurring in veins 
of no great thickness. 

In 1889, highly payable quartz veins were discovered at Kuaotunu, a locality distant some thirteen 
miles (direct line) from Coromandel. As these veins were of larger dimensions than those worked at 
Coromandel, and contained the gold more evenly disseminated throughout the ore, it was hoped that a 
more permanent field had been located, and the discovery was hailed with considerable satisfaction 

The outcrop of the main reef in the prospector's claim, the Try Fluke, yielded ore which assayed 
as high as 15 oz. of gold per ton, and a " rush " immediately set in, with the inevitable pegging-out of 
all adjoining areas. The Try Fluke vein or branches of this vein carrying payable values, were soon 
traced into the Mariposa, Red Mercury, Great Mercury, and other claims, and it was therefore con- 
sidered that here, at least, a permanent reefing-field existed. At a somewhat later date the quartz 
reefs of the Waitaia Mine, also located within the Kuaotunu Valley, were discovered. It was soon 
found, however that the gold existed in such a finely divided state in the Kuaotunu ore that the rather 
rough-and-ready amalgamation processes, which effected a fairly satisfactory extraction of the coarser 
gold in the Coromandel centre, were here altogether inadequate. Fine crushing and pan amalgamation 
was employed, with, however, only partial success until 1892, when the cyanide process was introduced, 
with an attendant reduction in the cost of treatment and a greatly enhanced extraction of gold and 
silver. 

From the date of its discovery up to the 31st December, 1906, the mines of Kuaotunu outturned 
gold and silver to the value of £190,795. Consistent as was the ore, however, of the Try Fluke reef 
system in the upper levels, a marked falling-off in value characterized that found to exist at greater 
depths, and the gold-returns inevitably showed a marked decline. 

The minor discoveries, in 1899, of gold-bearing veins at the Owera and at Lanigan's (Opitonui) 
are worthy of mention, as the localities lie midway between the old-established Coromandel centre and 
the newly discovered Kuaotunu area, and furthermore because these discoveries led to the extensive 
mining operations of the Kauri Freehold Gold Estates Comp ny in more recent years. 

The main Coromandel centre, which for several years previous to 1894 had experienced a period of de- 
pression, was destined yet again to demonstrate in unmistakable manner that the possibilities of a gold- 
field of this character can never be gauged, nor can it ever be deemed, like many an old alluvial field, 
•' worked out." The circumstances connected with the discovery of the bonanzas, which in 1894 brought 
the field again into prominence, are unique and deserving of record. These were located purely by 
accident in May, 1894, in a section of the mine owned and previously worked by the Coromandel Gold 
Company (registered in London). The Green Harp reef, already mentioned in connection with the 
rich ore-shoot discovered in 1872, occurred within the boundaries of the same claim, and together 
with other neighbouring and approximately parallel veins, constituted the principal ore-bodies operated 
on by the English company prior to this date. 

A certain amount of prospecting- work was previous to 1894 carried on by the Coromandel Gold 
Company in the section of their mine which now comes under notice, but this was mainly directed 
under the misapprehension that veins, or, rather, auriferous veins, were only likely to occur striking 
approximately parallel to those already discovered. Upon the cessation of active operations by the 
proprietary company the claim was subdivided into blocks, and each of these, down to the datum plane 
of sea-level, was let on tribute. Messrs. Ross and Colthurst, who were working one of these blocks 
from a small shaft, located a shoot of gold in a vein of minor dimensions, and elected to drive an adit 
level a distance of some 300 ft. in order to mine their ore more expeditiously. The contours of the 



17 

country necessitated that the outer portion of this adit should be driven through the tribute block 
held by Legge and party, and in this block the wonderfully rich vein known as Legge's reef, or the No. 2 
Hauraki reef, was intersected, striking almost transversely to the veins previously worked by the pro- 
prietary company. Legge and party, who previous to this discovery had worked for some eight months 
without return, had thus a rich bonanza vein discovered for them, and in the succeeding eight months 
of the term of their tribute, mined ore to the value of £11,928 I Is. 

The English proprietors immediately formed a new company, under the title of the " Hauraki 
Gold-mining Company (Limited)." with a capital of £40.000 (.'520,000 shares at 2s. 6d. each). The 
resumption of mining operations was attended with immediate and continued success: the bonanza 
of Legge's reef proved comparatively extensive, and. in addition to Legge's reef, many other valuable 
veins were located. 

The returns from the phenomenally rich veins of the Hauraki Mine, in addition to the steadily 
increasing gold-output from the Waihi and other properties situated in the southern portion of the 
Hauraki Division, precipitated the "mining boom" of 1895 to 1899— one of the 'greatest periods of 
raining excitement that the Auckland goldfields have ever experienced. The area pegged out 
as mining claims was relatively enormous, and prospecting operations were consequently ex- 
tended from the previously well-known centres to the hack country. 'Colonial capital for mine- 
development was largely supplemented by English capital, and numerous companies were formed 
principally to exploit properties situated in the older-estaUished centres. As is inevitable in all such 
periods of mining excitement, it cannot he affirmed that the expenditure of money was in all cases 
duly warranted, or that where expenditure was justified the mining operations were in every case in- 
telligently directed. 

The Hauraki Mine continued to hold its premier position throughout this period, OUttuming, 
from the Lai January, 1895, to :51st December, 1899. gold to the value of £239,915, and disbursing divi- 
dends to the shareholders ol £17(i.(MM) on the capital of £40,000. The Hunker's Hill Mine, adjoining 
the Hauraki on its northern boundary, will also long he remembered for the frequent and consider- 
able market fluctuations of its company's stock, although up to December, 1906, the mine only pro- 
duced -..Id to the value of £17,<M7. 

Among the English-owned mines of the Coromandel centre, in addition to the Hauraki, the Royal 
Oak Tokatea Amalgamated, the Kapanga, Scotty's 3 New Hauraki Gold Properties, I5la- 

grove'a Freehold. Kathleen Crown, I'reece's Point, and Golden Pah are worthy of record principally 
on account of the expenditure incurred in development. Excepting the payment of one dividend 
amounting to £12,500 by the Royal Oak ■ Tokatea Company, none of these properties gave any returns 

to the shareholders for the capital expended, although -onie ol them yielded gold, which partly Covered 
the cost of development. The amount of gold obtained will he given later in dealing with the special 
mining ,i 1 1 

At Kuaotunu further development-work was undertaken with the assistance of English capital. 

The Mariposa (originally the Try Fluke, old Mariposa, and certain adjoinin» areas), the (Jreat Mercury, 
the Irene, and the Waitaia were the principal claims which received attention. (."n fortunately no new 
finds of any importance eventuated, and work on the whole proved unremunerative. Probahlv the 
Waitaia claim was the only one ol these that returned sufficient gold to covei the cost of development 
and mining . 

In 1899 the Kauri Freehold Gold Estates (Limited) was registered in London, and acquired ex- 
tensive areas of freehold land in the Coromandel subdivision. This was financially the strongest com- 
pany that ever operated on the Coromandel Goldfield. and mining operations were centred chiefly 
on the comparatively large quartz veins which were known to exist in the Opitonui Valley within the 
main Whangapoua watershed. At the mine, shafts well equipped with pumping and winding machinery 
gave access to the underground workings on the veins. A modern forty-stamp mill with cyanide plant 
and all accessories was erected in a central position on the estate ; the mines and battery were con- 
nected with each other and with the Port of Whangapoua by a substantial railway. The mining and 
milling operations, extending over a period of four years and a half, resulted in 53,355 tons of 
ore being raised and treated for a gross return of gold and silver valued at £63,723. In the end 
2 — Coromandel. 



18 

the general verdict was that the veins were too low-grade to afford a margin of profit ; the abandon- 
ment of the enterprise therefore followed, and with it the almost complete removal of the surface-plant 
equipment. 

The mere tabulating of the names of the claims worked by local companies, syndicates, and private 
individuals during this period of activity would constitute a long list, and would serve no useful pur- 
pose. A few of these mines were remunerative, others gave small returns which partlv covered the 
cost of mining operations, but the great majority, as might have been anticipated, yielded no return 
whatever. Of the remunerative mines, the Four-in-Hand, situated in the Waikoromiko district, 
must be pronounced the most important, and may further be counted a new discovery. The com- 
pany owning the claim mined and crushed, during the years 1898 to 1906, 3,403 tons of ore for a 
return of £19,054 from which amount substantial dividends were paid on a small capitalisation. 

The handsome returns from the Hauraki Mine largely compensated the English investors for the 
losses sustained on the other properties on the Coromandel Goldfield. The subsequent exhaustion, 
however, of the bonanza ore opened up in the veins of this mine, and the failure of the feeble attempts 
to locate other ore-shoots therein, resulted in a rapid decline in the monthly gold-output. This was 
the immediate forerunner of a general collapse of most of the subsidiary companies. The gradual 
withdrawal of the foreign capital reflected on the colonial mining- market, with the inevitable result 
that the period of remarkable mining activity and the attendant general prosperity on the Coromandel 
Goldfield came to an end. The reaction which followed the " boom " has been far-reaching, and 
for the past five years or more the mining industry, on which Coromandel and its environs so greatly 
depend, has continued in a languishing condition. To a development in the Bunker's Hill was due 
the mild excitement of 1902-3, when a rich ore-shoot was discovered by tributers in a portion of the 
mine considered heretofore thoroughly exploited; this resulted in a gold- return valued at £11,547 
to the Bunker's Hill Company and its tributers, and about £4,500 to the Hauraki Freehold Company, 
the proprietors of the adjoining claim, into which a continuation of the shoot was traced. 

English investors still continue to hold a few mining freeholds, none of which are now being worked, 
and one Crown leasehold, the Waitaia Mine at Kuaotunu, which has up to the present time yielded 
returns sufficient to cover working-expenses. The other important Crown mining leaseholds' have 
been acquired by Auckland companies, and in Coromandel itself attention is now directed principally 
to the areas which have yielded the bulk of the gold of the past — namely, the Hauraki Mine and vicinity, 
Kapanga Mine and vicinity, Royal Oak Mine and vicinity. 

Mineral-production. 

The available data relative to the mining production in the early days of Coromandel, the oldest 
goldfield in New Zealand, are neither accurate nor easy to obtain. From the year 1886 the official 
returns issued by the Mines Department afford reliable information. 

Mr. T. W. Rhodes, the prime mover in the inauguration of the Gold Jubilee Exhibition held in 
Coromandel in 1902, succeeded in arriving at an estimate of £1,437,302 as the value of the gold-produc- 
tion from the opening of the field up to the 30th September, 1898. These figures have been quoted in 
the New Zealand Mines Record* and are probably as close an approximation as it is possible to obtain. 
In addition to this amount the official returns for the subsequent period brings the grand total to the 
31st December, 1906, up to £1,743,790. 

Having regard to the possible loss of old unofficial records, and also to the metal which may have 
been sold through other channels than the banks and not exported through the Customs, the figures 
quoted are much more likely to be under than over the true mark. 

It is not very clear how much of the value above stated should be accredited to silver, which occurs 
throughout this mining-field alloyed with the gold in the form of electrum ; probably £16,000 represents 
the minimum value of the silver produced from the opening of the field to the 31st December, 1906. 

In addition to gold and silver, a few tons of picked complex sulphide ore containing lead, copper, 
and zinc have been exported, but the value is almost negligible. 



* Vol. ii, 1898, p. 128. 



19 

Industries other than Mining and Quarrying. 

Agriculture. — Owing to the generally hilly character of the Cape Colville Peninsula the total area of 
the land suitable for farming is relatively small. Within the Coromandel subdivision the areas at 
present under cultivation are in general confined to the lower valleys of the various streams, more 
particularly to the flood-plains of streams entering the sea within sheltered inlets. 

As the rocks within the various stream-valleys differ in nature, so also do the soils which have 
resulted from their denudation and decomposition. The greater fertility of the soil derived from certain 
of the andestic rocks as compared with that from the old sedimentary rocks is well exhibited in some of 
the hilly grassed clearings. Again, the contrast between the bare, barren, rhyolitic country lying to 
flip east of the Whitianga Estuary, and the fertile plains of the andesitic area lying to the west is par- 
ticularly well marked. 

The most extensive tract of arable land within the subdivision is that just mentioned as lying 
on the western borders of the Whitianga Estuary, together with the long tongues extending up the 
valleys through which the Kaimarama River and its tributary the Mahakirau Hows before discharging 
into this estuary. 

This land is eminently suitable for dairying purposes, and it is a matter for surprise that no co-ope- 
ration of interests has yet been brought about to establish a central butter-factory. The deviation 
and improvement of the Whitianga-Coromandel Road, which is at present in progress, will greatly 
assist in the further development of the Upper Mahakirau Valley, where a fair proportion, even of the 
hilly country, appears to be suitable for the depasturing of sheep and cattle. 

At Coromandel the principal farming-lands fringe the harbour. Here a stretch of arable land, 
formed by the union of the flood-plains and fan deposits of the various streams, covers in the aggregate 
from two to three thousand acres and is subdivided into small holdings. Extending inland from the 
main area the flood-plains and lower slopes of the Waiau Valley are the portions which carry the most 
settlement. 

Most of the smaller outlying settlements, now dependent principally on agriculture, have been 
mentioned in other sections of this report, but the possibilities of more speedy development in the case 
of certain localities may here be indicated. 

The Maori settlements of Waiaro, Paparoa. Koputaiiaki. and Manaia, on the western coast-line, 
and Kennedy's Bay on the eastern coast-line, are all capable of much further development at a compara- 
tively low cost. Areas of fertile alluvial flats and easy-sloping sidelinga exist in the localities, on which 
tall manuka or light mixed bush is still standing. The value of this easily accessible timber for fuel 
would in part cover the cost of briimm<_ r these lands under cultivation. Again, certain tracts of land 
owned by private individuals or syndicates exist within the valleys of the various streams draining 
into Port Charles, Waikawau, and Whangapoua inlets on the east coast, and, though suitable for 
settlement, are at present lying idle. The clearing, grassing, and stocking of these areas would 
certainly be productive of payable results. 

During the present temporary depression in the local mining industry more attention is being paid 
to the agricultural possibilities of the district generally, and settlement is being gradually extended 
from the low grounds up the lower slopes of the ranges. At Coromandel, the main centre, cattle-sale- 
yards have recently been established, and plans for furthering the dairying industry are at present 
under consideration. 

All the fruits, vegetables, and cereals common to these latitudes are grown in favourable localities 
within the Cape Colville Peninsula, but the greater proportion of the land is more adapted for the 
depasturing of sheep and cattle. 

According to the agricultural statistics of 1907, the Coromandel County, which is, however, slightly 
larger than the Coromandel subdivision of the present survey, contains 22,054 acres of improved land 
under crops and grasses, and 96,482 acres of tussock, Native grass, and unimproved pasture-land. The 
stock-list shows 6.806 cattle, 1,011 horses, 14,954 sheep, and 716 swine, and these numbers are un- 
doubtedly capable of considerable expansion. In this connection the more energetic and successful of 
the farmers suggest that industrial experimenting should be undertaken more generally to ascertain 
2* — Coromandel. 



20 

what varieties of grasses are especially adapted to the various classes of land, and what fertilisers give the 
best results. 

Timber. — The timber industry has long been a very important one throughout the whole extent of 
the Hauraki Peninsula. 

The kauri {Agaihis australis) is by far the most abundant and most important timber for export 
and for local requirements. This is a tree which attains great dimensions, and grows in thick clumps 
at all elevations below 1,500 ft. It presents a long, straight, columnar barrel, normally from -1 ft. to 
10 ft. in diameter, often without a branch for 60 ft. The timber is light in colour, of comparatively 
low specific gravity, and possesses considerable strength and durability. The sawn kauri is graded 
by the merchants into three classes, and their values for various constructional purposes may be gauged 
from the fact that the listed prices of these in Auckland City are — first-class, 17s. 6d. ; medium, 
14s. 6d. ; and second-class, 9s. per hundred superficial feet. 

The rimu or red-pine (Dacrydium cupressinum). kahikatea or white-pine (Podocarpus dacrydioides), 
and totara (Podocarpus totara) are marketable timbers, which, however, occur to a much lesser extent 
than the kauri within this area. 

The value of mottled kauri, mottled rimu, and certain varieties of several of the other timbers in 
connection with cabinet-work and finer architectural work renders these worthy of special mention. 

Puriri (Vitex lucens) is a tree which affords a valuable hardwood, used for all purposes requiring 
great strain and durability, such as railway-sleepers, ground-piles, &c. In furniture and cabinet 
making also, this wood is rapidly coming into favour, being equal in figure and general appearance to 
the finest walnut. 

The pohutukawa (Metrosideros tomentosa) is especially sought after for use as knees and ribs in 
the construction of wooden vessels. 

Rewarewa, or honeysuckle (Knightia excelsa), furnishes a beautifully variegated timber used for 
inlaying, cabinetmaking, &c. 

Rata (Metrosideros robusta), manuka or tea-tree (Leptospermum scoparium and L. ericoides), are the 
hardwood timbers which occur in most abundance, and have the greatest value for fuel. 

In the particular portion of the Hauraki area under review the fact that the peninsula is narrow 
has rendered the forests more accessible, and has resulted in their depletion earlier than in the more 
southern localities. The remains of the dams which were used in impounding water to drive the logs 
out of the creeks still exist near the heads of many of the watercourses, and are vanishing evidences 
of the substantial contributions of this portion of the area to the total timber-output of the peninsula. 

Remnants of the kauri-forests are still being worked in the Cabbage Bay district and in the 
Te Pungapunga Valley, and timber to the extent of five or six million superficial feet is still standing 
at the headwaters of the Owera Creek. 

At Whitianga a sawmill giving employment to some fifty men, and having an output of about 
150,000 superficial feet of timber per week, is located on the northern shores of the Whitianga Estuary. 
The mill obtains its timber from the forests occurring within the valleys of the several streams which 
flow into the estuary from the country lying to the south. From the Port of Whitianga a consider- 
able amount of timber " in the round " is also shipped away to the Auckland sawmills. 

Kauri-gum. — Kauri-gum is the resinous exudation of the kauri-pine (Agaihis australis). It occurs 
at shallow depths in the hillside soils and clays, or is found at somewhat greater depths in the swampy 
alluvial grounds, thus marking the actual positions or near vicinities of the great kauri forests of past 
centuries. This burial in the earth for extended periods has had the effect of clarifying the resin, and 
thereby considerably increasing its value. The gum is used principally for the manufacture of varnish. 

The total amount of this product exported from the colony during the years 1853 to 1905, inclusive, 
was 226,165 tons, having a value of £12,920,531. This was practically all derived from the northern 
portion of the Auckland Land District, and, although the actual figures are not available, the Coro- 
mandel area may be considered to have contributed a fair proportion. 

The occurrence of the kauri-gum in the Hauraki Peninsula has had more than a direct value. It 
has afforded many a mine-prospector in the backblocks a means of subsistence while pursuing his 
ordinary calling, and not a few of the gold- discoveries of the remoter localities are attributed to the 
individuals who are at once gold-seekers and gum- diggers. 



21 

Flax. — The New Zealand Max (Phormium tenax) occurs at various localities throughout the area 
under consideration, though never in gre*at quantity. The Max grows most abundantly on the richer 
swamp lands, and here affords the fibre of best quality. That (P. cookianum) growing on the low 
wind-swept hills near Cape Colville is rather stunted and poor. 

Three' small (lax-mills are operating in the district, all on the eastern side of the peninsula. These 
are situated at Waikawau, at Whangapoua, and at Cook's Bay near Whitianga. The raw material 
for the mills is drawn in the main from the low grounds of the various coastal inlets, and is boated from 
these points to the milling localities. Considering the high price of the fibre at the present time, it is 
probable that many of the low tracts of rich alluvial land occurring in some of the coastal inlets could 
be profitably employed in the cultivation of this plant. 

Fishing. — Few portions of the New Zealand coastal seas offer better facilities for sea-fishing than 
does the Hauraki Gulf, the sheet of water separating the Cape Colville Peninsula from the mainland. 

The schnapper (Pagrus unicolor) is by far the most abundant of the marketable fish of these waters, 
while among the others the flounder (Hhombosolea monopus) and the mullet (Mugil ferusii) are perhaps 
the next in importance. The hapuka (Oligorus gigas), a valuable fish frequently found to weigh over 
801b., also inhabits certain portions of the rocky sea-floor. On the more sheltered parts of the rocky 
coast the rock-oyster (Ostrea ylomerala) is found in abundance, and as an edible she'!-fish is highly 
valued. 

Coromandel is the headquarters of a small fleet of fishing boats, which operate in the Hauraki 
Gulf near the western coast of the Cape Colville Peninsula. These boats transfer their lish to the 
coastal steamers trading to Auckland City, where a ready market is always available for the whole 
Supply. The opposite shores of the peninsula are. in the main, exposed to the full force of the 
easterly winds ; but small boats carry on fishing within shelter of the inlets and the islands near the 
coast. 

It is certain that the Ashing industry within the Hauraki Gulf, and even along the outer coast- 
line of the peninsula, will in course of time assume much greater proportions. 



22 



CHAPTER III. 



OUTLINE OF THE GEOLOOT 



Sequence of Formations 
Geological History 



Page 
22 
23 



Oeneral Structure of the Several Forma- 
tions 



Sequence of Formations. 

The oldest rocks existent within the area of the Coromandel subdivision are sedimentaries, belonging 
to three distinct series, and volcanics interstratified with what is apparently the most ancient of these 
series. 

Collectively these rocks constitute the folded and denuded stratified complex which has been 
frequently termed " the basement of the Cape Colville Peninsula." 

The three series involved in this complex, placed in their probable order of succession, have been 
designated in this bulletin — 

(a.) The Tokatea Hill Series ; 
(b.) The Moehau Series ; 
(c.) The Manaia Hill Series. 

The Tokatea Hill Series consists of argillites, grauwackes, and interstratified tuffs and lavas of 
acidic character. The interbedded volcanics. and certain rocks which appear to represent an admixture 
of the finer-grained pyroclastics with the ordinary sediments, constitute a very large part of the series, 
and markedly characterize it throughout the whole subdivision. 

The Moehau Series consists of a great thickness of thin-bedded argillites and grauwackes. which 
present considerable uniformity of character wherever they occur, and show no trace of contem- 
poraneous volcanic rocks. 

The age of the Tokatea Hill Series or of the Moehau Series is unknown, owing to the absence of 
palaeontological data. Both are certainly Pre-Jurassic. since they are overlain unconformable- by the 
rocks of the Manaia Hill Series, which contain Jurassic fossils. The relative position in tin- 
sequence of the Tokatea Hill Series and the Moehau Series is by no means evident in the area under 
review, since they have never been recognised as occurring in actual juxtaposition. The separation 
by the writers is based altogether on the lithological characteristics, which imply the deposition of the 
two series under very different conditions. The superposition, in the sequence, of the Moehau Series 
on the Tokatea Hill Series has been claimed by McKay,* who is the only previous investigator to suggest 
a subdivision of the basement rocks of the peninsula. His conclusions are based mainly on con- 
ditions obtaining beyond this subdivision. In deference to these conclusions, and in the absence of any 
evidence to the contrary, the writers, while assigning no definite age to the Pre-Jurassic rocks, have 
tentatively assumed that of the two the Tokatea Hill Series is the older. 

The Manaia Hill Series consists of conglomerates, grits, grauwackes, and argillites, which have 
been derived from the denudation of a land-surface consisting largely of volcanic rocks, both of inter- 
mediate and of acidic character. Lithological and structural conditions alike imply the unconformable 
superposition of the rocks of this series on those of the Tokatea Hill and Moehau Series. The Manaia 
Hill rocks have, on palseontological evidence, been assigned by the writers to the Jurassic period. 

Associated with the Tokatea Hill strata, intrusive igneous rocks abound ; with the Moehau strata 
such intrusives are of common occurrence, especially in certain localities ; in the Manaia Hill strata 
they occur very infrequently. In character these intrusives are intermediate or semi-basic, and occa- 

* McKay: " Rocks of the Cape Colville Peninsula," vol. i, 1905, p. 34. 



■ 








V 










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1 


H 


W$', 






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■ 


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■ "'j/.fw MPmH 



ERRATA. 

In the table of formations facing page 22, under heading " McKay, 
1905," transpose the subheadings "Middle and Upper Beds" and 
"Lower or Coal-bearing"; and after the word "Coal-bearing," insert 
the word " Series." 

On page 39, paragraph 3, transpose the words " and none of " in 
line 13 and the words " rendered the " in line 14. 



COX, 1882. 


PARK. 1897. 


MACLAREN, 1900. 


McKAY, 1905. 


Classification in this Bulletin. 




Pal.eozoic (Probably Devonian) *- 
Slaty shales and grauwackes 
(gold-bearing). 


Carboniferous (Maitai Slates 
of Hochstetter) — 
Slaty shales, grauwackes, sand- 
stones, crushed breccias, fel- 
sites, and felsitic tuffs.) 


Te Anau Series (Upper 
Devonian) - - 
Stratified beds of igneous 
material with associated 
eruptive and dyke rocks. 


1 

I 

a 
a 
Ph 


Tokatea Hill Series — 
Argillites and grauwackes, 
with interstratified beds 
of igneous materials. 


Lower Carboniferous and Upper 
Devonian — 
Slates, sandstones, and felsites. 


Maitai Series (Carboniferous) — 
Sandstones, slaty shales and 
mudscones, with intruded 
dyke rocks. 


Moehau Series — 

Argillites and grauwackes. 




Wairoa Series (Triassic) — 
Sandstones and conglomerates 
formed of igneous rocks, and 
slates and sandstones. 


Manaia Hill Series (Jurassic) — 
Argillites, grauwackes, grits 
and fine conglomerates. 


Cretaceo-Tertiary — 

Coal-bearing series of Cabbage 
Bay. 


Lower Eocene — 

Marine limestone, marly sand- 
stones, and conglomerates 
with brown coal. 


Lower Eocene — 

Clay marls, slate conglomer- 
ates, foraminiferal lime- 
stones, with small coal- 
seams. 


O 1 

a 
o 

H 

a 
« 
Q 


Middle and Upper Beds — 
Conglomerates, sandstones 
and shales with coal. 


Torehine Series (Lower 
Eocene) (?)— 
(a.) Conglomerates, sandstones, 


Lower or Coal-bearing — 
Marly greensands with 
concretions, compact 
limestone and calcareous 
sandstones. 


and shales with coal- 
seams. 
(b.) Marly sandstones, cal- 
careous sandstones, lime- 
stone. 


Age Doubtful — 

Auriferous rocks of the Thames. 
Breccias and tuffs. 


Upper Eocene-- 

Andesitic lavas, tuffs, and ag- 
glomerates (gold-bearing). 


Upper Eocene or Oligocene — 
Andesites (augite and 
hornblende], fresh and de- 
composed, fine-grained tuffs. 


t h a m 10 s-tokatea series 
(Eocene) (?)— 
Eruptive matter, mostly ande- 
sitic flow rocks, and breccias, 
&c, cut by dykes. 


Tertiary Volcanic Rocks of the 
"First Period" (Upper 
Eocene) (?)— 
Acidic : Rhyolitic tuffs. 
Semi-basic: Andesitic and 




Kapanga Series (Upper Eocene) — 
Same as above. 


dacitic tuffs, breccias, and 
lava-flows. 


Lower Miocene — 
Trachytic breccias. 


Miocene— 

Andesitic breccias and tuffs. 


Miocene — 

Trachytic and andesitic agglo- 
merates, breccias, and dykes. 


B E E s o N ' s Island Series 
(Miocene) — 
Eruptive matter wholly ande- 
sitic or dacitic ; stratified 
tuff beds with coal. 


Tertiary Volcanic Rocks of the 
•'Second Period" or 
Beeson's Island Series 
(Miocene) — 
Semi-basic: Andesitic and 
dacitic tuffs, breccias, and 
lava-flows. 


Pliocene — 

Rhyolite formation. 


Pliocene — 

Rhyolitic lavas and tuffs. 


[These acidic rocks do not occur 
in the area mapped by this 
writer.] 


a 
2 J 

o 

3 
a. 


Older Rhyolites (Whitianga 
Beds) — 
Breccia agglomerates 
mostly of acid rocks, 
pumiceous sands, &c, 
with beds of lignite. 


Tertiary Volcanic Rocks of the 
"Third Period" (Plio- 
cene) — 
Acidic : Rhyolitic tuffs, breccias, 




Mii'DLE Rhyolites — 

Massive flow and intrusive 
rocks. 


lava-flows. 




Pleistocene — 

High-level gravel terraces. 


Pleistocene — 

River-terraces, lacustrine beds. 


Raised Beaches (Post-Pliocene) — 
Coarse beach-gravels. 


Pre-Pleistocene, Pleistocene, 
and Recent — 
Unconsolidated or poorly con- 




Recent — 

River-flats, swamps, and blown 
sands. 


Recent — 

Alluvial flats, harbour-muds, 
swamp-deposits. 


Alluvial — 

Coarse gravel, river-deposits 
and finer sediments. 


solidated debris. River- 
terraces, river-beds, sea- 
beaches, drifting sands, talus 
slopes. 










Intrusive Igneous Rocks of 

various Periods — 
Acidic : Rhyolite. 
Semi-basic : Diorite, porphy- 

rite, andesite, dacite. 



T.- i,^ I o n „J laU » S Ti S ' Z .' ? nSt -'' % 1?'' ^"vj-t 1903, page 143, Prof. Park remarks: "Bocks belonging to the Jurassic system, in association with those of the Trias, form the greater portion of the Tararua, Ruahine, and 
isamian.iv,;, .uountains m the North Island ; and we have no reason to assume a greater age for the slaty shales, sandstones, and grauwackes which form the floor of the Hauvalci Peninsula." 
t Moehau beries of Geological Survey Bulletin No. 4, does not occur in the area mapped by this writer. 



Coromandel .] 



[To face page 22. 



23 

sionallv acidic. They are in greater part the analogues of Tertiary volcanic rocks ; but there 
is evidence to suggest that some of the intrusions in the strata of the Tokatea Hill and Moehau 
Series are referable to a period prior to that during which the Manaia Hill sedimentaries were deposited. 

Overlying the Jurassic and Pre- Jurassic rocks, and separated from them by a very marked 
unconformity, is a series of Lower Eocene(?) coal-bearing strata, which in this bulletin has been de- 
signated the Torehine Series. This series consists of conglomerates, sandstones, and shales, with coal- 
seams, marly and calcareous sandstones, and limestones, but is now represented only by isolated patches 
in a few separate localities. 

A great accumulation of volcanic rocks has in Tertiary times been extruded upon the eroded and 
markedly irregular surface of the Jurassic and Pre-Jurassic sedimentary rocks, and upon the few remnants 
of the Lower Eocene(?) beds which overlie these older terrain's. The Tertiary volcanic rocks are the 
products of three distinct periods of volcanic activity, and have in this bulletin been grouped under 
the following headings : — 

(1.) Tertiary volcanic rocks of the First Period. 

(2.) Tertiary volcanic rocks of the Second Period (Beeson's Island Series). 

(3.) Tertiary volcanic rocks of the Third Period. 

The rocks referred to the First Period consist of a greal pile of tuffs, breccias, and lava-flows. Rocks 
of andesitic and dacitic character largely predominate here, but those ol rhyolitic character are also 
represented. 

The rocks of the Second Period consist of heavy accumulations of andesitic and dacitic tuffs, breccias, 
agglomerates, and lava-flows. These extrueives have, by all previous writers on the geology of the 
Cape Colville Peninsula, been designated the " Beeson's Island Scries.'" Since the typical area lies 
within this subdivision, and the series named is so well established, it is in this bulletin used as an 
alternative in referring to the volcanics of the Second Period. 

The rocks of the Third Period consist wholly of tuffs and lavas of rhvo'itic character. 

Associated with the volcanic rocks here grouped under differenl headings, are intrusive rocks 
of varying lithological character. They are the products of different periods, and are no doubt coeval 
with many of the intrusive- existent in the old denuded sedimentary rocks. 

Unconsolidated and loosely consolidated debris is confined chiefly to the floors and embayments of 
the -treain-vallevs. and to narrow strips along the COast-line. In age most of the debris now visible is 
Pleistocene or Recent, but some of that which mining operations have shown to exist at considerable 
depths is probably earlier than Pleistocene. 

The tabulation facing page 22 sets forth the geological sequence as interpreted by the writer-, 
and also the classification- adopted by previous investigators. 

Gboloqical History. 

The argillites and grauwackes, which constitute the oldest rock- encountered in the Hauraki area, 
are the products of the denudation of a large land-mass. The position of the ancient land is perhaps 
impossible to determine, but from considerations both of palaeontology and the depths of the ocean 
surrounding New Zealand, it is generally assumed that the sediments were transported from the east- 
ward rather than from the west waul. Deposition probably took place not far from land, on a gradually 
sinking sea-floor, and, judging by the presence of fairly coarse sandstones, in no great depth of water. 
The products are those characteristic of large rivers draining a continental area, rather than of small 
island streams. 

The Tokatea Hill Series was laid down during a period marked by great volcanic activity, as 
evidenced by the numerous bands of acidic lava- and fine-grained tuffs interstratified with the ordinary 
sediments. Owing to the intimate mingling of the ordinary river detritus with these fine-grained tuffs, 
the resulting rocks show all gradations from argillites and grauwackes to the lighter-coloured highly 
tufaceous rocks. 

The Moehau Series, which consists of a great thickness of thin-bedded argillites and grauwackes, 
is indicative of a long-continued period of deposition, and a period which, in marked contrast to the 
one already mentioned, was unbroken by any manifestations of vulcanism. 



24 

There appears to be no evidence as to whether any considerable earth-movement intervened between 
the period of formation of the Tokatea Hill and Moehau Series, but it is certain that altered conditions 
of sedimentation marked the deposition of the overlying Manaia Hill Series. The rocks of the last 
series, consisting of conglomerates, grits, grauwackes, and shales, afford evidence of shallower-water 
conditions and contain undoubted Jurassic fossils. 

Prior to Jurassic times, and subsequent to the deposition of the Moehau Series, volcanic activity 
must have been much in evidence in the vicinity of the area under consideration. This is deduced 
from the fact that the Jurassic sediments contain an abundance of small pebbles of flow andesites and 
How rhyolites, as well as of porphyrite and other igneous rocks. The interstratified rhyolitic lavas 
forming part of the strata of the Tokatea Hill Series, might possibly be considered to have supplied the 
rhyolitic detritus forming part of the Manaia Hill Series. As to the locus, however, of the sheets of 
andesitic lavas requisite to supply such a large amount of detritus, one can only speculate, as no trace 
of such flow rocks has been detected in situ. Probably some of the numerous intrusions of porphyrite 
and diorite, associated with the strata of the Tokatea Hill and Moehau Series, represent the hypabyssal 
analogues of these Pre-Jurassic lava-flows. The very infrequent occurrence of intrusive igneous rocks 
in the Manaia Hill Series, and the less crystalline character of most of those that do occur — porphyrites 
and andesites (Tertiary) — afford considerable support to this conclusion. 

Subsequent to the deposition of the Manaia Hill Series there ensued the great orogenic movements 
which have determined one of the most pronounced breaks in the whole geological history of New Zea- 
land. The strata in the subdivision, consequent upon compressive forces acting in a general easterly 
and westerly direction, were folded and elevated. The flexures produced were so pronounced that 
in places the beds assumed a position of verticality. 

A long period of subaerial denudation followed, during which the crests of the anticlines were 
removed and the land-forms characteristic of mature topography were further developed. The Coro- 
mandel Peninsula was probably, at this time, part of a large land-mass, the mountainous character 
of which may be deduced from the remnants of the surface preserved at the base of the Torehine Series. 

The dawn of the Tertiary era saw this land-mass slowly submerged and receiving, in its river- 
valleys and estuaries, the fluviatile gravels and muds which have formed, on hardening, conglomerates 
and shales. The stage of maximum depression was marked by the deposition of limestone. The 
conglomerate, shales, marl, and limestone, which form what is termed in this bulletin the Torehine 
Series, are fossiliferous, and contain, in certain horizons, coal-seams marking pauses in the general 
positive movement of the shore-line. 

Immediately subsequent to the deposition of the limestone, the upper member of the Torehine 
Series, there ensued a second period of great orogenic movement resulting in a further folding and 
elevation of the strata. The compressive forces producing this folding appear to have acted in approxi- 
mately the same direction as those which gave origin to the late Jurassic folding. The fact that beds 
of the Torehine Series are found tilted at an angle of 45°, and that the isolated patches which are pre- 
served, within comparatively short distances, range in elevation from sea-level to 1,200 ft., is 
sufficient evidence of great differential earth- movements. 

Following, or in part contemporaneous with, the folding of the rocks, and to some extent the direct 
result of the orogenic movements, the stupendous volcanic energy which, with certain periods of inter- 
mission, has characterized the whole of the subsequent Tertiary era first manifested itself. Great 
piles of tuffs, breccias, and lavas were emitted from numerous volcanic vents, disposed in general north 
and south alignment along fissures or planes of weakness in the flexured sedimentary rocks. This 
great accumulation of material, which in places even now exceeds 2,000 ft. in thickness, has been 
grouped by the writers as the Tertiary volcanic rocks of the First Period of vulcanism. It is not, however, 
the product of a single continuous manifestation, but of several manifestations marked by pauses of 
greater or lesser duration, as evidenced by the intercalated seams of coaly material which occur in 
different localities. 

A period of quiescence followed the last outburst of these early Tertiary eruptions, and the 
mountainous land-forms, which were largely the result of original volcanic accumulation, were con- 
siderably modified by the agencies of subaerial erosion. In certain localities these volcanics appear to 



25 

have been entirely removed from the surface of the old sedimentary or basement rocks before the de- 
position of the volcanic ejectamenta of the next period. 

This extended period of quiescence came to an abrupt termination with the great volcanic out- 
bursts of the Second Period. The principal foci of eruption during this period were confined to the 
sea-coast on both sides of the peninsula, and the predominating explosive and paroxysmal character of 
the eruptions was probably due in part to the access of sea-water to the fissures or vents. The products 
of the eruptions consist of andesitic tuffs, breccias, agglomerates, and lava-flows. The accumulation 
of much of the fragmental material under subaerial conditions is indicated by the inclusion of shattered 
remnants of forest vegetation, now carbonised or silicitied. Further traces of this old land-vegetation 
are preserved as irregular coaly seams, which often mark the contact of these rocks with those of the 
earlier group. The closing manifestations of the vulcanism of this period appear to have been 
accompanied by the formation of numerous dykes intersecting the rocks of this and earlier periods. 

The rocks here grouped as belonging to the Second Period have been regarded as of Miocene age. 
and the evidence adduced in support of this conclusion, as presented on a later page, appears to be 
(airly satisfactory. 

The wonderful volcanic energy of the Tertiary era was. after another period of quiescence, Act 
again to display itself. Within the boundaries of the Coromandel subdivision, however, the 
products of this Third Period are confined to the extreme south-eastern portion of the area. They 
(•(insist of rhyolitic rocks both fragmental and massive, and thus are sharply demarcated from the 
intermediate or semi-basic rocks which form the great bulk of the earlier Tertiary volcanic complex. 
Further than that the rhyolites of this period must be considered to overlie the Miocene andesites, there 
is no evidence afforded within the area examined which fixes the period of their eruption. They have 
hitherto always been referred to a Pliocene age, from structural considerations in areas further south 
than that considered in this bulletin. 

The great deposits of siliceous sinter and chalcedonic quartz which characterize some localities ; 
the deep-seated alterations of certain belts "t the volcanics : the ore-deposits which these altered rocks 
frequently enclose ; are all evidences of former periods of intense livdmtherinal action. The structure 
of the volcanic pile, with its alternating beds of tuffs and lavas ; the general permeability of the rock- 
material filling ancient foci of eruption; and fault fissures and the fissures of contraction due to the 
cooling and consolidation of the rocks : all combined to afford conditions highly favourable for the 
vigorous subterranean circulation of aqueous solutions. These manifestations of hvdrothermal activity 
doubtless represented the "eruptive after-actions" which mark the dying stages of vulcanism. At these 
stages the heat still preserved in the rocks below the surface, and the gaseous emanations from deep- 
ted sources, supplied most of the motive power for the circulatory systems. 

Certain considerable earth-movements have affected the area since the later eruptions of the 
First Period. One of the greatest ,,| these movements is recorded in the existence of a nearly horizontal 
band of impure coal in the Kapanga Mine. Coromandel. at a depth of 700ft. below sea-level, indi- 
cating a depression of not less than the magnitude specified. This carbonaceous band, which is now 
highly pyritised and silicitied, is intercalated with fine tuffs or ash beds, in general it would appear 
as if movements of depression had affected the whole south-eastern portion of the area included within 
the Coromandel subdivision. .More recenl earth-movements, both of depression and elevation, took 
place in Quaternary times, resulting in the existing sunken valleys and raised beaches respectively. 

At the close of the Pliocene period all volcanic activity ceased in this area, and the main constructive 
geological work since that time has been the filling-up of the bays and inlets by fiuviatile agencies, a 
work which is still in progr> 

GrENBBAl STRUCTURE OF THE SEVERAL FORMATIONS. 

The strata of the Tokatea Hill, Moehau, and Manaia Hill Series have all been involved in the great 
orogenic movements of Late Jurassic or Post Jurassic times, and have in general a similar disposition. 
The folded complex appears to present the structure of an anticlinorium, with its principal axis in 
general alignment, though not in coincidence, with the trend of the main mountain divide. Owing 
probably to the effects of denudation, the youngest of these rocks — the Manaia Hill Series — are now 



26 

confined almost entirely to the lower flanks of this mountain-range. The folded strata, which are 
disposed at angles ranging in general from 40° to vertically, show no signs of metamorphism except in 
so far as they have heen locally affected by the numerous diorite and porphyrite dykes which frequently 
intersect them. The strike of these rocks, with the exception of local irregularities, generally varies 
from a few degrees east to a few degrees west of the meridional line. 

Orogenic movements must have affected the rocks of the Tokatea Hill and Moehau Series prior to 
the existence of the Manaia Hill Series ; the effects of these movements are now almost impossible to 
decipher, but they probably account for many of the variations from uniformity which exist in the pre- 
sent folded complex. 

The rocks of the Torehine Series occur on both sides of the peninsula, but only as small isolated 
patches. They are found at very different elevations, overlying in marked unconformity a rugged and 
denuded surface of the older rocks. They are generally disposed at angles varying from 10° to 20° from 
the horizontal, but angles approaching 40° have been observed. The elevation of these strata above 
sea-level was therefore attended with considerable differential movements. 

The Tertian- volcanic rocks of the First Period were apparently extruded after agencies of erosion 
had removed the greater part of the Torehine strata from off the older sedimentaries. They consist of 
irregularly stratified tuffs, breccias, and lava-flows ; the general mass of the rocks, especially in the 
lower horizon, is well consolidated. In vertical range they extend to elevations exceeding 2,000 ft. 
above sea-level, and in places pass below the datum-line of sea-level to an undetermined depth, exceed- 
ing 1,000 ft. 

The rocks of the Second Period — Miocene(?) — form considerable coastal belts. Agglomerates, breccias, 
fine tuffs or ash-beds, and lava-flows, constitute the main mass of these volcanics. The degree of con- 
solidation of the fragmental portion varies considerably, but in general is decidedly less than in the case 
of the pyroclastics of the First Period. 

Intrusive rocks in the form of dykes and sills are irruptive into each of the series already described. 
They are principally diorites, porphyrites, and andesites, and probably range in age from Pre-Jurassic 
to Late Miocene. 

Volcanics of the Third Period consist of fine pumiceous tuffs and flow rhyolites. The fragmental 
rocks are irregularly stratified and the inclination of the beds makes low angles with the horizon. The 
lavas appear to be younger and to have been erupted through these bedded tuffs. 

The deposits of unconsolidated debris, consisting of gravels, sands, and muds, forming the river 
flood-plains and the fringing coastal plains, have a slight dip seaward, and present the usual false- 
bedded structures common to such material. 



27 



CHAPTER IV 



PHYSICAL GEOGRAPHY. 



Page Page 

(ieneral Physiographic Features .. ..27 Streams — continued. 



The Main Divide and its Subsidiary Ridges . . 28 

(a. ) The Moehau Section . . .28 

(6.) The Cabbage Bay - Waiau Section . . 2(( 

(r.) The Waiau -Mahakirau Section . . 2ii 

The Outlying Ridges and Groups of Hills .. :{u 

The Lowlands . . . . . . . . 30 

Features of the General Coast-line . . 31 

Islands . . . . . . 32 



(b.) Streams chaining the Southern and 

Wider Portion of the Subdivision . . 35 

(<-.) Streams draining the Kuaotunu Penin- 
sula . . . . . . 3t> 

| il. ) Streams draining the Area lying to 

the East of Whitianga Estuary . . 37 

Springs- 



Streams 32 Hot Springs . . . . . . 37 

(a.) Stream draining the Northern and Cold Springs .. .. . . .'is 



Narrower Portion of the Subdivi- 



33 Water-power .. .. .. ..38 



General Physiographic Features. 

The Cape Colville Peninsula, also known as the Coromandel or Hauraki Peninsula, constitutes 
the eastern and much the smaller of the two projecting land-masses which form the northern limits 
of the North Island of New Zealand. 

This peninsula extends in a general north-south direction, and is separated from the 
larger physical feature, the North Auckland Peninsula, by the waters of the Hauraki Gulf. To the 
north and eastward of the coast-line of the Hauraki area only a few small islands break the broad ex- 
panse of the Pacific Ocean. The Great Barrier, the largesl of these outlying islands, probably formed 
at one time a northward extension of the Cap'- Colville Peninsula, and was separated from it by the 
agencies of marine erosion. 

The Coromandel subdivision of the present publication forms, as already indicated, the northern 
portion of the Cape Colville Peninsula. 

The survey district- of Colville. Moehau, and Harataunga together constitute the northerly and 
narrower portion of this subdivision, the distance from coast to coast here averaging a little over six 
miles. A short distance south of the area included in these survey districts, the land immediately attains 
a width of some twenty miles, due to the subsidiary Kuaotunu Peninsula, projecting eastward from the 
('ape Colville Peninsula. With the exception of the contraction in width caused by the deep inlet 
Mercury Bay. which determines the peninsular character of the Kuaotunu area, this lateral dimen- 
sion of twenty miles is preserved to and beyond the limits of the Coromandel subdivision. 

The surface of that portion of the Cape Colville Peninsula which is within the Coromandel sub- 
division is in general of broken and rugged topography. The Pleistocene(?) subsidence of this diversi- 
fied land-surface, with its numerous valleys, has afforded a relatively great length of shore-line, 
owing to the sea entering the irregularities of the land, and thus forming a typical rias coast. 

From any position of vantage, either at a prominent point along the shore-line or at an elevated 
altitude in the interior, one can easily discern that the physical feature which dominates the Coromandel 
subdivision is the main divide — a range of low mountains averaging 1,500 ft. in height, and extending 
from the north of the Cape Colville Peninsula to and beyond the southern limits of the subdivision. 
Running from the main divide subsidiary ridges are conspicuous between the numerous streams 
which incise the country and flow to either side of the peninsula. Minor independent ridges and groups 
of hills occur in places between the main divide with its subsidiary ridges and the coast-line on either 
side. These outlying ridges and groups of hills are usually not far from the sea-border. 

The mountainous country formed by the main divide and its subsidiary ridges, together with 
the minor independent ridges and groups of hills, forms by far the greatest part of the Coromandel 



28 

subdivision. The lowlands are inconspicuous : they are confined to fiats along the sea-margin, 
forming incipient coastal lielts, but little raised above high-tide level, and to narrow flood-plains 
extending from the lower pari of Ihe valleys of the main streams down to their mouths. 

The main physiographic features of the Coromandel area may be considered under the headings 
of— 

(i.) The main divide and its subsidiary ridges; 

(2.) The outlying ridges and groups of hills ; 

(3.) The lowlands. 

The Main Divide and its Subsidiary Ridges. 

The main divide and its subsidiary ridges are together known as the Cape Colville Range. In the 
northern and narrower portion of the subdivision the crest of the range is almost equidistant from 
either shore ; but in the southern and wider portion it lies nearer to the western than to the 
eastern coast. The general trend of the axial divide, considered from its northern extremity, is 
about south 50° east for a distance of about 10 miles, and thence south 18° east for a further distance 
of 18 miles, to the Waiau Saddle. From the Waiau Saddle to the boundary of the Coromandel subdivi- 
sion (3^ miles) the trend, as will be mentioned later, departs considerably from the normal south-by- 
easterly direction. 

For the sake of description these three portions marked by their different trends may be respectively 
designated (a) the Moehau Section, (b) the Cabbage Bay - Waiau Section, and (c) the Waiau-Maha- 
kirau Section. Each will be separately discussed, together with the subsidiary ridges jutting from 
the several sections of the divide. 

(a.) The Moehau Section. — The Moehau section of the Cape Colville Range constitutes both the 
most elevated portion in the subdivision, and the portion in which the old stratified rocks play the 
most prominent part in the structure. This section is known popularly as the Moehau Range. It is an 
area consisting essentially of highly folded argillites and grauwackes which are intruded and indurated 
by numerous dykes and sheets of igneous rocks, and consequently has offered considerable resistance 
to the agencies of subaerial erosion. The more easily weathered effusive volcanics form only the 
south-eastern portion of the Moehau section of the main divide. 

The dominating and central feature in the section is Te Moehau Mountain, which rises 2,935 ft. 
above the sea, and presents from any point of view a decidedly massive appearance. At 25 chains 
south 75° east of the main crest of Te Moehau, and separated therefrom by a minor depression, stands 
a sharp conspicuous peak of only some 50 ft. lower elevation. This pinnacle owes its existence to the 
resistance to denudation given by the massive hornblende andesite, which occurs as an extrusion at 
this point. 

From the wind-swept summit of Te Moehau, with its covering of subalpine vegetation, the elevation of 
the Cape Colville Range gradually decreases to a point some 35 chains in a north-westward direction, 
where a general altitude of 2,700 ft. is reached — a height which is preserved for a stretch of some one and 
a quarter miles. From here radiating spurs separated by deep valleys gradually fall to the level of the 
bold headlands of the northern coast-line. 

Immediately to the south-east of the rocky peak of Te Moehau, the elevation of the water-parting 
decreases to about 2,500 ft. From this sudden descent the actual divide shows minor prominences and 
depressions until Trigonometrical Station H 6 is reached at an elevation of 2,054 ft. South from this 
trigonometrical station the ridge continues to fall for a distance of three miles : at first rather steeply 
then gradually until the boundary of the Moehau section is reached in the Cabbage Bay - Port Charles 
Saddle (500 ft.). This saddle, in which creeks flowing to the opposite sides of the peninsula have their 
sources, forms by far the lowest depression in the whole main range, and is crossed by one of the graded 
roads connecting settlements on each side of the divide. 

The thickly wooded flanks of the Moehau section of the Cape Colville Range are deeply incised by 
numerous high-grade^streams, with the consequent development of bold leading spurs descending 
from the axial divide to the actual sea-borders. Abrupt scarps, due in part to the existence of dyke 
rocks, are not uncommon. The steepest rock-faces are those overlooking the headwaters of the 



29 

streams draining into Stony Bay on the eastern coast-line. An initial fall of some 1,800 ft. in half a 
mile, may in places be here observed, with below this a more gradual descent of about 1,000 ft. to sea- 
level. 

(b.) The Cabbage Bay- Waiau Section. — In the Cabbage Bay - Waiau section of the Cape Colville 
Range the older sedimentary rocks rarely reach to the crest of the axial divide, and it is to the over- 
Lying volcanic accumulations that the mountain-range mainly owes its height. The average strike 
of the strata in this section approximates fairly closely to the trend of the main range. This section 
of the main divide, in its trend from the low saddle (500 ft.) which separates it from the Moehau 
section, presents at first only minor elevations — from 800 ft. to 1,000 ft. — but further south a height of 
1,500 ft. is attained, and preserved to the saddle some 60 chains north-north-east of Trigonometrical 
Station HI. where an old track, connecting Cabbage Bay with Kennedy's Bay, crosses. From this 
saddle the divide trends more towards the westward for a stretch of three miles, and presents fairly 
uniform elevations of 1,700 ft. to 1.800 ft. after the rather sharp initial rise from the saddle to 
Trigonometrical Station HI. Continuing southward the divide preserves a fairly straight south-23°- 
east course for eleven miles, to the Waiau Saddle. 

The most conspicuous heights of tin Cabbage Bay- Waiau section of the Cape Colville Range are, 
named in order from north to south, Te Ranga, or Look-out Rock, about 1.700 ft.; Tokatea Hill, 
1,577 ft.; Trig. Hill IT, 1,852 ft.; Kaipawa, or Success Hill, 1,935 ft. ; Castle Hock, 1, 721ft.; and 

Motutere, 1,763 ft. 

The four first-named peaks call for little note physiographically, but in Castle Rock is presented 

the most salient feature of the whole landscape. As viewed from the Hauraki Cull, it is a bold castel- 
lated crag having its Longer axis coincident with the general trend of the axial divide. The mountain 
rises from a comparatively low saddle having an elevation of about 1.080 ft.. at firs! with moderately 
steep slopes and finally with precipitous cliffs on three sides fur the upper 400 ft. Castle Rock forms 
the most prominent outcrop of a great dyke of dacite which traverses the main divide in this vicinity. 
The mountain owes its local relief to the agencies of Bubaerial erosion, which have effected the removal 
of the easily weathered tuffs and lavas which the dyke has intruded. 

Motutere (1,7(53 ft.) though slightly higher than ( lastle Rock is not nearly so conspicuous. The same 
dyke that forms Castle Rock forms Motutere, and gives rise to the very steep rugged country on both 
tin- eastern and western flanks of the main divide in tin- locality. 

Saddles are not of common occurrence in the Cabbage Bay Waiau section of the Cape Colville 
Range. The well-known Tokatea Saddle lies just to the south of the Tokatea Hill, where the Coro- 
niandel - Kennedy's Bay Road crosses at an elevation ol aboul 1.200ft. The Whangapoua Saddle, where 
the Coromandel Kuaotunu Road crosses the mam range, has an approximate elevation of 1, 200ft. 
The Opitonui Saddle (1,080 ft.), in the vicinity of Castle Rock, has already been mentioned, while 
further south, at the end of this section of the range, the Coromandel Mercury Bay Road crosses the 
divide at the Waiau Saddle (1.155 ft.). 

The character of the flanks of the range in the Cabbage Bay Waiau section is fairly well indicated 
by the directions assumed by the various stream-valleys. These directions vary from an approximate 
parallelism with the main divide, through all intermediate angles to a transverse direction, and hence 
there arises a rather diversified topography. The spurs present lairlv rounded outlines and, being in 
general capped with disintegrated rock-debris and vegetable mould, rarely show the rock in situ. The 
long, straight, outrunning ridges met with in Bfoehau Range with its more nearly transverse 
streams, do not often occur in the section under consideration. 

(c.) The Waiau- Mahakirau Section. — This section of the main divide, which extends from the Waiau 
Saddle to the southern boundary of the Coromandel subdivision, is only three and a half miles in length, 
but is noteworthy as showing considerable departure from the usual trend of the range. From the 
saddle named, the divide bears south-west for about two miles and then regains and preserves its normal 
course of south-by-east to the boundary of the subdivision. No marked features characterize this stretch, 
which has a general elevation of 1,300 ft. 



30 

The Outlying Ridges and Groups of Hills. 

It is difficult to precisely demarcate the ridges and spurs subsidiary to the main divide, and forming 
with it the Cape Colville Range, from the minor outlying ridges and spurs of hills nearly independent 
in origin and separate topographically from the main divide. For instance, sometimes ridges which 
are apparently quite distinct and individual are in reality merely separated by a low and inconsiderable 
saddle from a spur jutting from the main divide. Under the present heading will be considered only, 
(a) certain more or less definite ridges close to both coast-lines, which owe their origin to the accumu- 
lation of the volcanic ejectamenta of the Beeson's Island Series; (b) the ridge of hills on the Kuaotunu 
Peninsula ; and (c) the hilly rhyolitic country east of Whitianga Estuary. 

(a.) The explosive volcanic action of Miocene(?) times, along both coast-lines, has given rise to 
accumulations which now exist on the mainland, as comparatively low hills and ridges, and off the coast- 
line, as islands. On the western coast-line the low peninsular ridge and the hilly Beeson's Island, forming 
the north-western boundary of the Coromandel Harbour, come under this heading, and likewise the 
bare hilly country extending from the southern shores of Coromandel Harbour to Manaia Harbour, 
having a maximum elevation of 620 ft. From the south side of Manaia Harbour to Kirita Bay the 
same volcanic accumulation forms the elevated country which culminates in the sharp peak Pukewha- 
kataratara at 1,293 ft. above sea-level. On the eastern side of the peninsula the accumulations of the 
Miocene eruptions, subsequently modified by subaerial erosion, have given rise to the hills, ridges, and 
spurs, showing little definite arrangement, which form the coastal belts between Port Charles and 
Whangapoua Harbour. 

(b.) The Kuaotunu Peninsula has a general trend in a direction transverse to the central rib of the 
Cape Colville Range, and is dominated by a ridge which strikes away from the main divide at a point 
between Castle Rock and Motutere, and is in part to be considered with that feature rather than as 
independent therefrom. On the summit of this ridge, and distant about 70 chains from the main 
divide, rises Pinnacle Rock, which resembles in outline a huge shark-tooth, and is yet another portion 
of the intrusion to which Castle Rock owes its existence. Further eastward from Pinnacle Rock the 
dominant heights which occur at fairly regular intervals on the ridge are Hikurangi ; Hukarahi, 
935 ft ; ' Waitaia Hill, 1,032 ft. ; and Tahanga, 686 ft. The rocks forming this stretch of country 
are mostly volcanics of the Beeson's Island Series, and afford topographical outlines modified and 
rounded by subaerial erosion. 

Independent of the main ridge of the Kuaotunu Peninsula are several isolated hills, the most 
conspicuous being Te Tutu (636 ft.), an ancient volcanic vent near the northern coast-line, and Manga- 
tawhiri (985 ft.), a massive volcanic pile in a corresponding position on the southern coast-line. From 
Waitaia Hill (1,032 ft.) on the dividing ridge of the Kuaotunu Peninsula, a bold subsidiary ridge, 
known as Waitaia Ridge, extends in a direction north 32° west, terminating at the northern coast- 
line in Black Jack (702 ft.), a conspicuous hill which overlooks the lower township of Kuaotunu. 
This transverse ridge, which is the most conspicuous physical feature in the Kuaotunu Peninsula, 
consists of folded sedimentary rocks, and is probably the only existing remnant (on the mainland, at 
any rate) of an old line of elevation parallel to the main axis of the Cape Colville Peninsula. 

(c.) The area lying ^to the,' east of Whitianga Estuary, and forming the south-eastern portion 
of the subdivision, consists of volcanic accumulations, subsequently modified by subaerial erosion. 
The hills, which consist of acidic tuffs and lavas, attain a maximum height of 670 ft., and present no 
definite arrangement. 

The Lowlands. 

As already remarked, the lowlands form a very small portion of the Coromandel subdivision, 
and occur as comparatively isolated areas. These comprise narrow flats close to the sea-margin, which 
represent incipient coastal plains formed by marine denudation and sedimentation, and the alluvial 
flood-plains of various streams which occur, almost entirely, within a short distance of the sea. They 
are most extensive when the flood-plains of two or more streams coalesce. 

On the eastern coast-line the Whitianga flat, bordering the western side of the estuary of the 
same name, which debouches into Mercury Bay, together with the tongues extending up the valleys of 



PLATE IV 





jailffSiir* 


.. - 


»-^ 




m -*J^^^^^| 


''^s!*** 














— -2^ vz^^v ' jt-.il ihiLmfAflMMMM 



Wait.ua Kidge and Black Jack Hill, from Materanqi. 

[Photo, by Mr. Alex. McKay, F.G.S. 




Te Tutu Volcanic Neck, viewed from the Eastward. 

[Photo, by Mr. Alex. McKay, F.6.S. 



Geo. Bull. No. ',.] 



[To fact //. 30. 



31 

the Mahaldrau and Kaimarama Rivers, forms by far the most extensive lowland area in the Coromandel 
subdivision. Further north, similar but smaller flats are found close to the mouths of the streams 
draining into Whangapoua Harbour, Kennedy's Bay, Waikawau, Port Charles, and Stony Bay. At 
Whangapoua Harbour, Omaro Spit, a long tongue of low-lying country, extends in an easterly direc- 
tion from the hilly country of the Kuaotunu Peninsula, and determines the barrier between the 
open ocean and the shallow tidal mud-flats of the harbour. This spit has an area of some 1,093 acres, 
and is bordered near its outer margin by a long line of sand-dunes. 

On the western coast-line the low grounds fringing the inner shore of the Coromandel Harbour, 
and extending back to the foothills of the ranges, probably form the largest single lowland area. The 
coalescence of the flood-plains and fans of many streams — chief among which are the Waiau and the 
Whangarahi, and their tributaries — contribute to the formation of this strip of country. The flats 
bordering the inner shores of the more contracted inlets, Manaia Harbour, Koputauaki Bay, Cabbage 
Bay. and Waiaro, and extending up the lower portions of the stream-valleys which debouch at these 
points, are the largest of the other lowland areas of this side of the peninsula. 

Fringing the base of the Moehau Range on the western coast -line from the mouth of the Darkie 
Creek to Hope Creek ia a long narrow area with a low inclination seaward. This gradually sloping 
land is formed by the overlapping fans of the various high-grade streams (lowing off the mountain- 
range, and by the downward gravitation of talus from the higher country. Relatively recent elevation 
of the land has increased the area of low-lying country in this locality, the negative movement of the 
strand being shown by raised beaches in the neighbourhood of Ongahi Creek, Waiaro Creek, and else- 
w here. The small bay of Port Jackson is bordered by a narrow lowland area, the product mainly 
of fluviatile and fluvio-niarinc deposits, with sand-dunes close to the shore-line. In addition 
to the sand-dunes mentioned as existing at Port Jackson and at Whangapoua, similar deposits 
also mark the exposed shore-line of Kuaotunu, Mahinapua, and Cook's Bay on the east coast. 

Practically all the lowland areas so far described are either true flood-plains — the results of fluvia- 
tile deposition, or coastal belts — the products of Huvio-inarine deposition which have been recently 
uplifted above the sea. Flats of any extent due to marine denudation are rare ; but very narrow 
shelves which border cliffs facing the open sea occur in several places. They are horizontal, or nearly 
so, and entirely submerged at high tide. Rocky shelves of such nature are common features of the 
coast of the peninsula. On the eastern coast-line may be mentioned those between Port Charles and 
Handy Bay, and between Cape Colville and the Sugar Loaves ; on the western coast line may be noted 
those to the north and south of Goat Bay and at the headlands of IV Kouma and Manaia Harbours. 
These shelves are occasionally 100 ft. or more in width at low tides. The mud-Hats occurring in the 
sheltered inlets of the coast-line testify to relatively large areas of marine deposition. 

Features of the General Coast-line. 

The present coast-line testifies to two distinct secular movements since the land-forms of the Coro- 

lel subdivision assumed what is practically their present character. The numerous deep bays, the 

irregular promontories, the occasional sunken river-mouths, and the many outlying islands point to a 

former pronounced downward movement : while the raised gravel beaches and the mud-flats now partly 

elevated above high-tide level are indications of more recent upward movement. 

The exposed eastern shores present, as might be expected, more broken and sinuous outlines than 
those of the opposite side of the peninsula. The principal inlets of this eastern coast-line — namely, 
Stony Bay, Port Charles, Kennedy's Bay, Whangapoua Harbour, and Mercury Bay, with the minor 
indentations of the latter — namely, Whitianga Harbour and Cook's Bay — have in other connections 
already been mentioned. The inner shores of all these inlets exhibit at low tide gradually shelving, 
spacious mud-flats, through which ramify the channels of the various streams. Fairly long stretches 
of sandy beach form the actual shore-line in certain localities. The most extensive of these are Mata- 
mataharakeke beach (1 mile), Kennedy's Bay beach (1J miles), Te Pungapunga beach (1 mile), Whanga- 
poua beach (2 J miles), Mahinapua beach (2 miles), Buffalo beach (2 miles), and Cook's beach (1£ miles), 
the two latter being within the main Mercury Bay inlet. 



32 

Rocky headlands, steep cliffs, narrow tidal Ledges or shelves, outrunning reefs, minor indentations 
and caves, short boulder beaches, and outlying rocky islets, are all conspicuous features of the remain- 
ing portions of this eastern coast-line. 

The coastal features of the country lying to the east of Whitianga Estuarv which are due to marine 
denudation, are rather different from those of any other portion of the subdivision, owing to the 
difference in geological structure of the area. The almost horizontallv bedded fine pumiceous tuffs 
give rise to conspicuous light-coloured vertical or undercut cliffs. Outlying stacks and projections 
here frequently present rather fantastic shapes. Some are sharp isolated masses while others, above 
the reach of the waves, are connected with the mainland. One huge tunnel, eroded through a headland 
a mile and a half north-west of Wigmore Creek on the eastern coast-line, measures 130 ft. in length by 
50 ft. in width, and has a mean height of 30 ft. from its sandy floor to its well-arched roof. Narrow 
beaches in places border these cliffs, and are traversable at low states of the tide. 

Shakespeare Cliff (elevation 288 ft.) is a bold precipitous headland lying just to the west of Cook's 
Bay, a sandy-beached minor indentation of Mercury Bay. These three names — Shakespeare Cliff, 
Cook's Bay, and Mercury Bay — bear reference to an interesting incident. Shakespeare Cliff is the 
spot where Captain Cook, in 1769, observed the transit of Mercury, and in Cook's Bay the navigator's 
vessel took up her anchorage. 

At the extreme north-west of the Cape Colville Peninsula is the picturesque bay of Port Jackson, 
with its wide stretch of sand beach, and rugged promontories flanked by the rocky island-stacks to the 
east and west. Along the western coast-line, between Port Jackson and Cabbage Bay, rough 
rocky cliffs flanked by narrow rock-ledges, alternate with short, sandy beaches, or with much 
longer boulder-strewn beaches. Cabbage Bay is a spacious inlet with wide stretches of mud-flat 
visible at low water, and bordered in places by rugged cliffs. Southward from Cabbage Bay are the 
deep indentations of the coast-line known as Koputauaki and Kikowhakarere Bays, while still further 
south is the broad harbour of Coromandel. This harbour, measuring about three and a half miles by 
two miles, has two entering-passages, separated by Beeson's Island. The wild rocky coast from 
the main entrance of this harbour, southward to the lirnits of the subdivision, is deeply indented by 
Te Kouma and Manaia Harbours and the much smaller Kirita Bay. The two former inlets show in 
their inner reaches the usual extensive tidal mud-flats, incised by the winding channels of the various 
streams. 

Islands. 

The many islands which lie at no great distance off the shores of that part of the peninsula 
included within the Coromandel subdivision represent portions of the mountainous mainland, which 
have become separated therefrom in the many and varied tectonic changes which the area has 
undergone. 

Of these numerous islands, only those lying off the western coast-line from Manaia Harbour to 
Cabbage Bay need be specially mentioned. The examination of the larger insular areas — namely, 
Great Barrier Island, Mercury Islands, and Cuvier Island — and the numerous islets lying to the 
north or west of the peninsula, has, as before stated, been deferred till another season. 

Of the many islands off the western coast-line, Waihau or Beeson's Island, at the entrance of the 
Coromandel Harbour, is the largest. Geologically and topographically this island, volcanic in its origin, 
is representative of the whole group. It has, relatively to its area, considerable relief above the ocean 
level, and is girdled by a much-indented coast-line. Its tussocked or bushed slopes sometimes fall 
gradually to the shores of the small sandy bays, sometimes terminate in abrupt cliffs of greater or 
lesser heights. These cliffs in places pass almost vertically below the lowest tidal mark, whilst else- 
where they are skirted by heavy talus debris resting on a rocky marine shelf or a fringing shingle 
beach. Streamlets are of course very small, but water is also afforded by small springs which issue 
near the coast-line. 

Streams. 

The streams of the Coromandel subdivision exhibit normal conditions of drainage, and such as 
might be expected in a region of considerable relief free from complicating features of glaciation, &c. 
All the main streams rise near the mountain divide, and generally flow through small flats Dear 



PLATE V. 




Shakespeare Clipp, Mercory Kay 

[Photo, by Mr. Alex. McKay, F.G.S. 




Wiiitiaxga Rock, Mercury Bat. 

[Photo, by Mr. Alex. McKay, F.G.S. 



Geo. Bull. No. }. ] 



[To face p. 



PLATE VI. 




The Coast-line North-east of Waitaia Ridge. 

[Photo, by Mr. Alex. McKay, F.G.S. 




Materangi Bluff, with Black Jack Hill in the Distance 

[Photo, by Mr. Alex. McKay, F.G.S. 



Geo. Bull. No. /,.] 



[To face f. 33. 



33 

their mouths. In the mountains their courses are often sinuous, with wild deep gorges, now broken 
by large or small waterfalls, again by rapids or cascades of considerable length. On the lowlands the 
streams meander, flowing with gentle current broken occasionally by inconsiderable rapids. 

In the lowlands they are practically flowing at grade, and owing to the greater rapidity of fluviatile 
than of subaerial erosion this condition is usually continued backwards a considerable distance into 
the mountains. Slight departures from normal drainage conditions, depending on the nature of the 
underlying rocks of the country, wall be exemplified later. 

The generally elevated and rugged character of the district, together with its relatively small area, 
precludes the existence of large streams ; few carry a sufficient volume of water to warrant their being 
described as rivers, and most of them, with propriety, are locally termed creeks. 

For convenience of description the streams of the subdivision have been grouped as follows : — 

(1.) Streams draining the northern portion of the subdivision ; 

(2.) Streams draining the southern portion of the subdivision, excepting those contained 

under heads (3) and (4) ; 
(3.) Streams draining the Kuaotunu Peninsula ; 
(4.) Streams draining the area lying to the east of Whitianga Estuary. 

(1.) Streams draining the Northern Portion of the Subdivision. — This area may be defined as all 
that north of a line drawn from Coromandel Harbour to Whangapoua Harbour. 

Throughout this portion of the peninsula the mountain divide occupies a median position ; this 
determines watercourses of approximately equal length to the eastern and western coast-lines. The 
streams How naturally in directions more or less transverse to the trend of the main divide, but a con- 
vergence of streams to certain coastal inlets is more or less apparent. These latter phenomena are 
such as might be looked for in a drainage-system set up on a land-surface, whose physiographic features 
in early Tertiary times were the direct result of the effusion of volcanic materials from many vents. 
Modifications of pre-existing drainage appear to have been effected by the Tertiary eruptions of the 
"" Second Period." It would seem that in certain localities, depressions were formed between the ac- 
cumulations resulting from these coastal eruptions, and the flanks of the older land. In these depres- 
sions, which had for some distance directions more or less parallel to the main divide, drainage-channels 
were established which captured some of the older transverse streams of the higher country and re- 
ceived small tributaries from the coastal side. Examples of drainage of this kind are given by the 
Umangawha Creek, on the western side of the divide, flowing north into Cabbage Bay, and by the Whare- 
roa Stream on the eastern side, flowing south into Kennedv's Bay. 

The watercourses of highest gradient naturally occur in the more elevated portion of this area 
— namely, the Moehau Range. Here the country consists of indurated argillites and grauwackes with 
intrusive dykes and sheets of igneous rocks, a structure which offers considerable resistance to fluviatile 
erosion, and gives rise to narrow gorges, waterfalls, deep rock-bound pools and rapids — features 
not uncommon, especially in the upper portion of the streams. Not infrequently, when a dyke 
occurs striking approximately parallel to the direction of the watercourse, the stream may be 
observed following the contact of the dyke and the intruded rock for a considerable distance, 
with a course not so sinuous as is ordinarily the case. South of the Moehau Range the effusive 
volcanic rocks overlie the old folded sedimentaries and take a greater part in the structure of the 
country. Wider-open valleys with gentler-sloping sidelings usually characterize stream incisions 
in these more easily eroded rocks. Intrusive rocks and beds of hard comparatively unaltered lavas 
and indurated breccias, however, are sufficiently resistant in places to give rise to more rugged features. 
More contracted valleys, with falls, pot-holes, gorges, &c, become noticeable where the streams have 
cut down to the level of the old indurated sedimentaries. 

The streams flowing to both coast-lines are numerous, and only the most important need be men- 
tioned. In the extreme north Bronlund Creek, draining the termination slope of Moehau Range, 
and the much smaller Huriwai Creek, skirting the western base of the low subsidiary ridge which 
ends at Cape Colville, flow into the sand-bordered bay of Port Jackson. The smaller creek forms swampy 
lagoons before breaking through the piled-up sand-dunes of this exposed locality. On the east 
coast Holland Creek is the largest of several small streams discharging on to the broken coast- 
3 — Coromandel. 



34 

line north of Stony Bay. Into the latter bay the whole drainage of the rough eastern flanks of Te Moehau 
Mountain is delivered by converging streams which join together before reaching the lower ground 
skirting the shore-line. At the headwaters of these creeks small streamlets carrying the drainage 
of the crests and upper flanks of the mountains, tumble over the precipitous rock-faces which have 
been mentioned as occurring in this locality. Big Sandy Bay Creek, the Tangiaro and Kerr Creeks, 
entering the Port Charles Inlet, drain country consisting in the main of effusive easily eroded andesites, 
consequently their gradients are normal and their valleys more open than those of the Stony Bav creeks. 
Further south the Waikawau Stream, flowing in a general south-easterly direction, discharges on to the 
exposed sandy beach of Matamataharakeke. Up to a point some two miles from its mouth this stream 
is tidal, and at about 30 chains from the mouth it is joined on its right bank by its chief tributary, the 
Waikanae. These streams, except near their actual headwaters, present very easy bed-gradients. The 
hilly country of the main range and subsidiary ridges lying to the north, west, and south of Kennedy's 
Bay give rise to a number of relatively small streams which join the Harataunga before or after it reaches 
the estuary debouching into the north-west corner of the bay. The streams named in order from north 
to south are the Whareroa, the Mataiterangi with its tributary the Mangatu, the Wairakau, the Omoho, 
the Waverley, the Harataunga, the Waikoromiko, and the Kopurukaitai. The rocks of this drainage- 
area which is roughly semicircular in shape, consist partly of effusive volcanic rocks and partly of 
older sedimentaries with frequent igneous intrusions ; the valley-forms are those which, as already 
described, characterize such areas. 

Te Pungapunga Creek is a fairly large stream, draining the hilly andesitic country lying between 
Kennedy's Bay and Whangapoua Harbour. It flows in its middle and lower courses through a wide 
open valley, and discharges on to an exposed sandy beach. 

The Waitekuri and Opitonui are the two most southerly streams of the eastern side of the narrow 
part of the peninsula under consideration ; the valleys of both expose only andesitic rocks and exhibit 
the usual topographical characteristics. The waterfalls and gorges, consequent on the intrusion of 
the Castle Rock dyke, are prominent features in the headwater branches of the Opitonui Creek. 

On the western side of the main divide the low flanks of the Moehau Range are scored by numerous 
small high-grade streamlets, and at intervals by somewhat larger creeks, which receive the drainage 
of the higher portions of the range. ' Among the larger streams may be mentioned Fantail, Darkie, 
Ohinewai, Ongahi, Hope, and Neilson Creeks, all debouching on the open coast-line. In their upper 
courses the bed-gradients are high, narrow gorges and waterfalls being of frequent occurrence. In 
their lower courses these streams meander through a narrow, fringing, alluvial area with a gentle sea- 
ward inclination ; this area in the main owes its existence to the overlapping, widely spread fan debris 
from the several streams. The Waiaro, further south, is a stream rising on the saddle which indents 
the main range between the Waiaro and Port Charles Settlements. Its headwater branches incising 
indurated sedimentary rocks, broken through at various points by eruptives, present the usual topo- 
graphical forms. About a mile and a half from the sea the flood-plains begin as a narrow wedge 
and gradually widen out to a width of about 40 chains at the shore-line. Low cut banks mark 
the limits of the present creek-bed winding through this lowland portion of the valley. 

The small creeks flowing into the Ahirau Bay have their origin in the lowest saddle of the main 
divide, which lies between Trigonometrical Stations I (1,086 ft.) and C (803 ft.). After the usual steep 
descent from their headwaters these streams all flow through low-lying swamps to the marginal 
mud-flat of the upper portion of the bay. 

The fairly large Umangawha Creek, flowing northward into Cabbage Bay, has already been men- 
tioned in connection with its somewhat abnormal course. Grassed and bushed flood-plains form the 
base of the main valley from the Barney Creek junction to the shores of Cabbage Bay, a distance of 
about three miles. The headwaters of the main stream and its chief tributaries, Sutton, Barney, and 
White Star creeks, flowing from the eastward, cut through volcanic rocks overlying hard indurated 
sedimentaries. In its upper course Barney Creek plunges over precipitous faces of compacted rhyolite 
tuffs in a conspicuous fall 390 ft. in height. Branch Creek, the main westerly tributary, has cut its 
valley partly in the andesites of the coastal belt, partly in the Torehine beds and in the older sedi- 
mentaries. 



35 

On the coastal belt between Cabbage Bay and Koputauaki Bay, the largest streams are 
Anthony, Tawhetarangi, and Paparoa Creeks. Anthony Creek presents a unique feature in the 
drainage conditions of the Coromandel district, owing to the existence of limestone within its 
watershed. The stream disappears from the surface, and after following underground passages 
for some distance emerges at a lower level. The Wkaiwango (Big Paul's) Creek and its main left-hand 
tributary. Little Paul's Creek, have their origin near the main divide. The upper portion of the valley 
is carved in the more easily eroded effusive volcanies, but the bed-rock of the middle course with its 
gorges and waterfalls consists of the resistant strata of the Tokatea Hill Series. The flood-plain 
forms the usual roughly triangular area, having as its base the shores of the Koputauaki Bay, into 
which inlet the stream debouches. Following the coast-line southward the small Kikowhakarere 
Stream, flowing into the bay of the same name, is encountered a mile and a half from Coromandel 
Township. 

In the Coromandel Valley the Whangarahi and the Karaka, which junction on the alluvial plain 
shortly before reaching the inner shore of the Coromandel Harbour, are the chief drainage-channels. 
Tributary streams are numerous, many delivering into the main channels only after the low grounds 
skirting the foothills of the range are reached. Steep descents, as usual, mark the upper courses of all 
the streams. Tertiary volcanies and the old sedimentaries arc the rocks traversed, and have their 
usual influence on the topographical forms and scenery of the valleys. 

(2.) Streams draining the Southern Portion of the Subdivision, except those contained under 
Heads (.'}) and (4). — The increase in the width of the peninsula in this section, which lies south 
of the line drawn from Coromandel Harbour to Whangapoua Harbour, gives rise to an increased 
drainage-area and consequently to larger streams. The divide here does not occupy a median 
position, but lies nearer the western than the eastern coast -line, and this determines the greater 
drainage-area in the latter direction. 

Practically the whole of the eastern watershed considered in this section is drained by the Maha- 
kixau River. This stream, with its tributaries, collects the drainage of the eastern side of the whole 
stretch of the main mountain divide from a point half a mile north of Motutere to and beyond the 
southern boundary of the subdivision. 

Since the Tertiary volcanies, massive and fragmental, which constitute the rocks of this water- 
shed, have offered no great resistance to fluviatile erosion, the main valleys are generally of an open 
V shape, even far back in the mountains. A rapid descent continued for a short distance from the 
actual stream-origin (elevation about 1/200 ft.) near the crest of the main range, followed by a long, 
very gradual fall to the -ea-level, is the profile which characterizes the stream-bed of the Mahakirau 
and that of its chief tributary, the Waitakatanga, even more than the many other streams of this sub- 
division. The lateral streams draining the flanks of the main river-valley, being naturally of high 
gradient throughout the greater part of their courses, show successions of waterfalls and rapids with 
small contracted gorges. From the foot of the initial steep descent of the Mahakirau, with its water- 
falls and cascades, the stream flows with a sinuous course through a narrow valley over a boulder- and 
gravel-strewn bed of gradually diminishing gradient. Contracted gorges still occur at intervals as 
well as inconsiderable rapids followed by fairly deep pools. The further diminution of gradient is 
accompanied by low, bushed flood-plains, alternating along the stream's course, and rock in situ is 
observed only at intervals. These are the characteristics of the Mahakirau down to its junction with 
its main left-hand tributary, t the Waitakatanga. From its junction with the Waitakatanga, a stream 
which shows conditions similar to the main drainage-channel, the valley opens and the alternating 
flood-plains increase in width. These conditions continue throughout a distance, measured in a 
straight line, of two miles and a quarter, to the confluence of the stream with the Kaimararaa. 

The Kaimarama River enters the subdivision flowing from a west-south-westerly direction, and 
meanders through the flood-plains of a wide open valley. It joins the Mahakirau with a volume of 
water approximately equal to that of the latter. • From this junction it flows for a distance of three 
miles through fertile flats, finally debouching into an arm of the Whitianga Estuary. 

The Waiau River, the Awakanae Creek, and the Mill Creek discharging into the Coromandel Harbour, 
the Manaia River flowing into the Manaia Harbour, and the Kirita Creek into Kirita Bay are the 

3' — Coromandel. 



36 

principal streams draining the main western watershed of this section of the subdivision. Of these 
drainage-channels, those of the Waiau and the Manaia arc much the largest, and are the only ones 
that call for further description. 

The Waiau Stream rises in the Waiau Saddle, which has an elevation of 1,155 ft., and is situated 
70 chains to the south of Motutere (1,763 ft.). This saddle is that in which the main branch of the 
Waitakatanga originates. The Waiau flows from this saddle in a general north-westerly direction : 
thus its course makes only a small angle with the trend of the axial divide, and its largest tributaries 
rising in the high country of the main range enter from the eastward. The main stream presents a 
fairly regular gradient, its gradual descent below the actual headwater slopes being interrupted only by 
a single fall of some 30 ft. in height. This feature, which is dignified by the name " Waiau Falls," is 
about a mile from the crest of the divide. The existence of indurated sedimentary rocks in the 
middle course of the stream gives rise here to contraction in the width of the valley, but at a dis- 
tance of a mile in a straight line, or a mile and three-quarters following the bends, from the margin of 
Coromandel Harbour, the stream enters upon and meanders through the fertile alluvial plain known 
as Tiki Flat, 

Those tributary streams of the Waiau entering from the eastward have their origin in the country 
lying between Castle Rock and Motutere, and fall abruptly over precipitous scarps, the walls of the 
Castle Rock dyke. One of these, Motutere Creek, in three closely consecutive steps descends 325 ft.* 
The Matawai Creek, one of the largest of the easterly tributaries, preserves a uniform gradient from 
its steep headwaters to within 45 chains of its junction with the Waiau. At this point a thick stratum 
of indurated quartzitic grauwacke gives rise to the Matawai Falls, which, in a distance of 5 chains, 
have a total drop of 80 ft. From the foot of these falls the stream-bed shows but slight inclination 
and meets the Waiau at grade. 

The Tiki Creek, which in its upper portions flows in a general southerly direction, drains a large 
part of the flanks of the main range in the rear of the Coromandel Harbour. The stream presents 
normal characteristics, and joins the Waiau in the alluvial plain, at about a mile and three-quarters 
from the point where the main stream enters the tidal mud-flat of the inner border of the harbour. 

Only the middle and lower courses of the main Manaia River lie within the limits of the subdivision. 
Its main tributaries, however, the Taurarahi and the Tupa, entering the main channel from the east- 
ward, lie wholly within the area considered. The main stream has in general a north-westerly course, 
and where it crosses the southern boundary of the subdivision its valley is somewhat contracted 
owing to the existence at this point of resistant strata of the Tokatea Hill Series. A narrow gorge 
for a distance of 30 chains marks this portion of its course. From the headwaters of the main stream 
in the area south of that under consideration to the gorge portion mentioned, a quite normal gradient 
was found to obtain. Below the gorge the stream falls very gradually, and a mile down is joined on 
its northern side by the Taurarahi at an elevation of 20 ft. From this junction the stream incises its 
flood-plains, which from here gradually increase in width to the swampy borders of the Manaia Harbour, 
a mile and three-quarters distant. On its course through the flat the stream is joined by the Tupa, 
draining the country lying to the north-east. The Taurarahi and the Tupa have cut their valleys 
partly in volcanic and partly in sedimentary rocks, and present normal physiographic features. 

(3.) Streams draining the Kuaotunu Peninsula. — This section includes that area north-east of a 
line drawn from the mouth of the Opitonui Stream to the entrance of the Whitianga Harbour. 

The water-divide lies nearer the south-eastern than the north-western coast-line, so that the larger 
streams are those flowing in the latter direction. Of these, the Owera, Otanguru, Mapauriki, Kuaotunu, 
Otama, and Stewart may be mentioned. With the exception of the Kuaotunu Stream, their valleys 
are incised in Tertiary volcanics, and present the normal topographical features. Swampy alluvial 
flats mark their lower and sometimes their middle courses, and, as might be expected, these streams 
are frequently tidal for some distance from their mouths. 

The Kuaotunu Stream has incised its valley principally in the old indurated sedimentary rocks, 
with the result that the valley-flanks are much steeper than those which incise the rapidly weathering 



* The height of waterfalls and similar minor topographic features are barometric. 



37 

volcanics of the other creeks mentioned ; particularly is this the case in the headwaters of the main right 
branch in the vicinity of the Waitaia Mine workings. Old stream-loops and small lagoons occur in 
the rear of the coastal sand-dunes, and narrow flood-plains extend for a relatively long distance up 
the valley. 

Of the streams flowing to the southern shore of the Kuaotunu Peninsula those of the outer 
portion of the peninsula are very small and of high grade, flowing over rapids and falls which continue 
to the actual coast-line. Further south-westward somewhat larger streams effect the drainage of the 
area, the principal of these being the Kohurahorao, Waitaia, Woodcock, Akeake, Tarapataki, and 
Taputapu. 

(4.) Streams draining the Area lying to the East of WkUianga Estuary. — This area, unlike any of 
those already considered, consists essentially of puiniceous tuffs and solid rhyolitic lavas, with the 
result that the drainage-channels exhibit special characteristics. The higher country is of the modified- 
plateau type, and often consists of hills showing little definite arrangement, consequently the trends 
of the water-divides are very irregular. 

The typical profile of one of the larger streams of this section exhibits a steep descent for a very 
short distance from its source, followed by a stretch of low gradient terminated by a waterfall, and 
below this comparatively swampy ground through which the stream meanders to the coast-line. 

A feature of these watercourses is the relatively great extent of the swamps. These are not confined 
to the low-lying Hats, but occur in the watercourse-valleys of the higher country, extending almost 
to the water-divides. This is apparently due to the porosity of the pumiceous tuffs which take such 
a large share in the formation of the country. A great part of the rainfall is absorbed by these rocks 
and is transmitted very gradually to the watercourses, thus affording a fairly continuous supply of 
moisture to the valley-beds, and so favouring the growth of rank swamp vegetation. The absorption 
and transmission of surface waters by these porous rocks is also evidenced by the springs, which will 
be described later as occurring at the base of the slopes near the sea-border>. 

The principal streams are Flax-mill (reek, which breaks through the sandhills of the first beach 
eastward of the mouth of Whitdanga Kstuary. Cook and Purangi Creeks flowing into Cook's Hay, 
Wigmore and Orua Creeks draining the extreme eastern part of the ana. Of these, Purangi Creek 
is the largest, and all its branches debouch into a comparatively large estuary, a typical sunken river- 
valley some one and a half miles in length. 

Springs. 

The springs of the Coromandel subdivision, although inconspicuous natural features, are both of 
popular and scientific interest, and of some economic importance. They may, on a temperature classi- 
fication, be considered under the headings of (a) hot -jinn.:- and (f>) cold springs. 

Hot Springs. — The thermal springs in the district under review are phenomena of considerable 
interest, but the fact that such exist appears to be not very generally known, even in the neigh- 
bourhood of their occurrence. 

These hot springs are found only in the vicinity of Mercury Bay. and are apparently confined to 
the area covered by the products of the latest period of volcanic activity, the rhyolitic rocks. Two are 
known to occur in the subdivision, one at Taputapu Creek, which debouches on to Buffalo Beach, 
Mercury Bay, and the other in the valley of Wigmore Creek, Purangi, in the extreme south-eastern por- 
tion of the subdivision. 

At Orua or Hot Water Beach, on the eastern coast-line just beyond the southern boundary of the 
subdivision and two and a half miles south from Wigmore Spring, is a hot spring to which reference 
will be made for comparisons. 

Taputapu Hot Spring : This spring is located in the actual bed of the Taputapu Creek, near the 
Buffalo Beach, and just a few feet on the seaward side of the footbridge where the main Whitianga- 
Kuaotunu Road crosses the creek. The hot water issues from the sandy creek-bed, which is unfortu- 
nately covered at this point by some 4£ ft. of water. Notwithstanding this depth of overlying creek- 
water, the temperature of the bottom silt is about 120° Fahr., that of the water midway between the 
bottom and the surface 100° Fahr., and at the surface 95° Fahr. Unfortunately, no sample of the 



38 



spring-water could be obtained for analysis, but it certainly appears to have a value for pathological 
purposes. Dr. Robert Bedford of Auckland, formerly in charge of the Mercury Bay Hospital, to 
whom the writers are indebted for the temperature-observations, writes, " The water in this pool had 
the property of alleviating fatigue in a remarkable degree ; a bath in it was an excellent restorative 
after a long and tiring journey." 

Considering that this spring is situated within 70 chains of the Mercury Bay Hospital, it is rather 
surprising that no attempt has been made to turn it to useful account. It is probable that the 
fissured rock from which the hot water emanates lies only at a small depth below the bed of the 
creek, otherwise the temperatures observed could not be maintained under such adverse conditions. 
The lower slope of the hills skirting the flat is distant about 17 chains to the northward of the spring, 
and shows rock in situ. In order to exploit the spring, pipe-sinking might first be attempted, in the 
hope that the hot water would rise above the level of the creek and thus be conveyed where required. 
Failing this method, the diversion of the creek might be practicable. 

The Wigmore Spring : This spring occurs on the right bank of Wigmore Creek, some 40 chains 
from the mouth. The hot water at present issues from low swampy ground skirting the rhyolitic hills, 
but the actual site is rather difficult to locate owing to the dense scrubby vegetation which covers the 
area. It is said that strong puffs of steam emanating from the swamp are particularly noticeable in 
cold weather. Maori legends refer to the former existence, on the lowest portions of the hill-flank 
here, of a fine pool used for bathing purposes. This, it is said, was overwhelmed by a landslip, causing 
the, waters to issue from their present more unfavourable position. No water was procurable for analysis. 

Both of the springs described are undoubtedly to be referred to the rise of heated waters through 
deep-seated fissures in the volcanic rocks, as is also the Orua Hot Spring just outside the subdivision. 
The latter occurs on a sandy beach between the tide-marks, and storms at times lay bare the fissured 
rock. 

The analysis of a sample of water taken from the Orua Spring is here submitted, as it may indicate 
the character of the waters of the springs within the Coromandel subdivision. (Results expressed in 
grains per gallon.) 

Potassium-chloride . . . . . . . . . . . . 7-2 



Sodium-chloride 
Calcium-bicarbonate 
Calcium- chloride 
Magnesium - chloride 
Silica 



200-8 

22-5 

21-6 

1-8 

5-5 



Total .. .. .. .. 259-4 

Dr. Maclaurin remarks, — 

" The absence of all but minute traces of sulphates shows that no appreciable amount of sea-water 
has gained access to the spring. 

" The water belongs to the class of muriated saline waters found at Kawhia, Gisborne, &c. 

" Most of the hot springs of this class in New Zealand contain iodine, but none could be detected 
in this water in the small amount available for the test." 

Cold Springs are of infrequent occurrence in the subdivision, and afford only small volumes of water. 

On Beeson's and certain other islands springs issue near the coast-line, and afford a constant supply 
of water even in the summer season, when the streams on the island become almost dry. At Purangi, 
on the eastern side of Whitianga Estuary, the springs of cold potable water, issuing in places from the 
pumiceous tuffs, are a great boon to the inhabitants, since rank swamp growth occurs in all the creeks 
and renders the water unsuitable for drinking purposes. 



Water-power. 

The comparatively limited area constituting the Coromandel subdivision, together with its salient 
physiographic features, precludes the existence of streams carrying, under normal conditions, any con- 
siderable volume of water. 



39 

The larger streams — namely, the Mahakirau, the Manaia. and the Waiau — however, would appear 
at first sight to warrant some consideration as sources of motive power, but further examination does 
not confirm such a conclusion. The profile of any one of these streams, considered from mouth to 
source, is that of a line having a very slight uniform rise for much the greater part of its length, 
followed by a sharply rising curve near its termination. The major volume of water is contributed 
to the trunk channel at relatively low elevations by numerous tributary streams ; consequently, long 
before the necessary elevation for the intake of a water-race is attained, the volume of water in the 
main channel has become quite inconsiderable. 

While no stream exists in the area which would afford adequate power for transmission to the 
mining centres, small high-grade streams are, as might be expected, of frequent occurrence in certain 
localities. The latter, liowever. are only of value as limited sources of power, if such power should be 
required in their immediate vicinities. 

The abnormally high rainfall experienced during the summer season of 1906-7 and none of 
measurement of the volumes of water carried by the streams altogether unsatisfactory, rendered the 
the results obtained are herein submitted. A tabulation of volumes upon which any reliance could 
be placed is possible only as the result of several accurate measurements, extending over a lengthy 
time-interval. The only single measurement that can have much value is one made when the 
stream has fallen to almost its minimum volume. Such measurements were seldom or never 
possible duiing the extremely wet season mentioned. 



40 



CHAPTER V. 



PRE-JURASSIC AND JURASSIC STRATIFIED ROCKS. 



Introduction 

The Tokatea Hill Series 
General Statement 
Age and Correlation 
General Distribution 
General Structure 
Petrology 

The Moehau Series 
General Statement 
Age and C orrelation 



'age 
40 


Page 
The Moehau Series — continued. 


41 


General Distribution . 


. . 40 


41 


General Structure 


. . 47 


41 


Petrology 


. . 47 


41 


The Manaia Hill Series . 


. . 48 


42 


General Statement 


. . 48 


43 


Age and Correlation . 


. . 48 


4ti 


General Distribution . 


. . 50 


46 


General Structure 


. . 51 


4(5 


Petrology 


.. 51 



(Pre- Jurassic. 



Introduction. 

Pre- Jurassic and Jurassic stratified rocks constitute the oldest visible terranes in the Coro- 
mandel subdivision. In the northern portion of the area they form the whole of the main mountain- 
range, while further south they constitute the basement or core of that range, or underlie the volcanic 
rocks at various depths. Considered collectively they have extent throughout the whole length of the 
peninsular area under review, but the exposures are not continuous at the surface owing to the heavy 
overmantle of volcanic rocks. 

Structural and lithological considerations, which will be discussed later, have led to the subdivision 
of these stratified rocks into three series, designated in this report — 

(a.) The Tokatea Hill Series) 
(b.) The Moehau Series. j 
(c.) The Manaia Hill Series. (Jurassic.) 

The main orogenic movements which primarily determined the Pre-Tertiary land-forms of this 
area have involved the rocks of all these three series collectively, and it is therefore convenient to con- 
sider here the general disposition of the rock-complex as a whole. 

The mapping of the strikes and dips of the strata throughout the whole area reveals great irregu- 
larities, even apart from the inevitable local deformations due to the intrusions of igneous rocks. The 
predominant strike of the strata throughout the whole area may be said to vary from 25° east to 25 c 
west of the meridional line. The general trend of the peninsular mass and also of its axial divide, 
considered from the southern boundary of the Coromandel subdivision, is north-north-west to south- 
south-east for a distance of some twenty miles, and then, in the Moehau section, north-west to south- 
east for the remaining twelve miles. The strike of the rocks therefore presents a general parallelism 
to the trend of the greater part of the mountain-range, but crosses at a considerable angle the trend 
of the northern portion of this range. The beds appear to be disposed as an anticlinorium, the main 
structural axis of which lies in the main slightly to the eastward of the major portion, and altogether 
to the eastward of the minor Moehau portion of the main mountain-range. Within this anticlinorium 
small subsidiary folds appear to exist both to the eastward and westward of the mountain divide. In 
addition to the actual disposition of the beds as a whole, the distribution of the Jurassic sediments, 
the youngest of the folded complex, suggests general anticlinal arrangement. These sediments form 
a belt on the lower flanks of each side of the mountain divide. As in one or two cases they are found 
to approach, or attain to, the crest of the divide, it would appear that agencies of subaerial erosion 
prior to Tertiary times had effected an almost complete removal of these beds from the crown of the 
fold. 



41 

The Tokatea Hill Series, 
general statement. 

The rocks of the Tokatea Hill Series, which are probably the oldest in the district, consist of 
argillites, grauwackes, and intei stratified beds of igneous material both fragmental and massive. In 
addition, rocks exist showing every phase of lithological gradation between the ordinary sedimentaries 
— argillites and grauwackes — and the interbedded pyroclastics. The rocks of this series present the 
same mineralogical characteristics wherever developed in the area, and are largely intruded by dykes 
of porphyrite, andesite, and rhvolite. Though highly folded, the bedded rocks show no evidence of 
dynamic metamorphism, and even in the vicinity of the igneous intrusions are only slightly and 
locally affected by contact metamorphism : they are, however, over considerable areas, altered and 
pyritised by the same agencies which have effected the propylitisation of considerable masses of the 
overlying andesitic rocks. 

AGE AND CORRELATION. 

The age of the Tokatea Hill Series is unknown owing to the absence of palseontological data. 
That the rocks are of Pre-Jurassic age is certain, as in the Manaia Valley they underlie uncon- 
formable grits and hue conglomerates which, on Manaia Hill some three miles away, have yielded 
Jurassic fossils. The Manaia Hill beds, moreover, contain pebbles of igneous rocks which have 
been derived in part from an area bthologically similar to the Tokatea Hill Series. Unconformity 
between the particular series under review and the Manaia Hill Series is very evident from a con- 
sideration of the section- exposed in the Tiki Creek with its tributary the Pukewhau, and in the 
Matawai ('reek. Only a narrow- hushed ridge separate- the two valleys in question, which an- approxi- 
mately parallel to each other. The strike of the lieds at similar elevations in each valley is transverse 
to the trend of the valleys, and yet the lithological character of the rocks in the two valleys is altogether 
different. Moreover, the Tokatea Hill Series in the Tiki Creek shows numerous dyke intrusions of 
porphyrite striking towards the Matawai Valley, hut the rocks of the main Matawai Valley (Manaia 
Hill Series) show nowhere any sign of these intrusions. 

The relationship between the Tokatea Hill Series and the Moehau Series is not nearly so evident, 
since the rocks do not occui in actual juxtaposition as do those of the two series already considered. 
Possibly some small area of the rocks of the Moehau Series occurs in the low grounds of the Waiau 
and Matawai Valleys, and has been included with the Manaia Hill Series, owing to the difficulty in 
the field of distinguishing the finer-grained sediments of one series from those of the other. If such 
is the case tin' same reasoning would apply as regards unconformity of the strata of the Tokatea 

Hill and Moehau Series. The separation of the Tokatea Hill and Moehau Series, however, is based on 
lithological rather than on structural considerations. The stratified beds of igneous material which 
everywhere characterize the Tokatea Hill Series are evidence of a period of sedimentation during 
which volcanic action made great display, and such evidence is conspicuously absent from the exten- 
sive exposures of the strata of the Moehau Series. 

Mi Kay* is the only previous writer who has suggested a subdivision of the rocks of the area under 
review into three distinct series. He assigns to the Tokatea Hill rocks a Devonian age, and considers 
them older than the Moehau Series of the present bulletin, which he refers to the Carboniferous period 
from lithological similarity to the rocks of the Maitai Valley, Nelson — a classical Carboniferous area. 
The present writers have no evidence to offer for or against these conclusions, but, while leaving the 
age an open question, they incline to the opinion that the Tokatea Hill Series is older than the Moehau 
Series. 

GENERAL DISTRIBUTION. 

The rocks of the Tokatea Hill Series have, in the subdivision, their greatest development on the 
western slopes of the main range, but are also found on its crest and on its eastern slopes. 

On the western side of the range the most northerly outcrop of the rocks occurs as a small inlier 
surrounded by andesites, in the valley of the Whaiwango Creek (Rig Paul's Creek) in the vicinity of 
its main junction. 



* Sollas and McKay : " Rocks of Cape Colville Peninsula," vol. i, 1905, p. 34. 



42 

South of the'Tokatea Hill area, which will be later described, they are met with in Maddern 
( reek and in Courthouse Creek, in each case showing in the creek-bed for a distance of nearly a quarter 
of a mile immediately to the eastward of the Tokatea " Big Reef." 

Further southward occurs the largest exposure of these rocks in the subdivision. This exposure 
has, on the Success Road, a width of about 35 chains and extends from 350 ft. to 650 ft. above sea-level. 
Passing southward from here this width increases, until in Cadman Creek the Tokatea rocks cover 
over a mile and a halt : they also form in this locality the tongue extending out into the alluvial flat 
south of the Coromandel Township and known as " Green Hill." From Cadman Creek this exposure 
preserves a general south-south-easterly trend, to its point of termination just below the junction of 
the Matawai Creek with the Waiau River. The average width of this portion of the belt is about a 
mile, the stratified rocks extending from the edge of the alluvial plain or the very low andesitic foothills 
to elevations ranging from 650 ft. to 1,000 ft. on the western flanks of the main range. These rocks 
in Tiki Creek, which incises this belt, are as typical of the series as those of the Tokatea Hill area. 

The Tokatea Hill Series is overlain by the Manaia Hill Series to the southward of Tiki Creek. On 
the map a line extending in a north-easterly direction from the Matawai Creek - Waiau River junction, 
and passing about 12 chains west of Pukewhau Saddle, marks approximately the contact of the two 
series, both being overlain at an elevation of 880 ft. by the Tertiary volcanics. At a distance of 35 
chains east of Pukewhau Saddle along the Tiki-Opitonui Track, rocks characteristic of the Tokatea 
Hill Series are again conspicuous, forming an inher surrounded partly by Jurassic strata (Manaia Hill 
Series) and partly by Tertiary volcanics. 

In the Manaia River Valley occurs the most southerly development of these rocks in the subdivision. 
They extend from the fork of the main stream up the right branch for a distance of 33 chains, and up 
the left to and beyond the limits of the subdivision. This exposure as far as mapped is an inlier in 
Jurassic strata. 

The area which includes the Tokatea Hill and Saddle — the typical locality — lies, in the main, 
on the eastern slopes of the mountain divide. The rocks are much altered, and the boundaries are often 
very poorly demarcated, the disintegrated shoadings of the numerous porphyrite dykes closely simulat- 
ing the andesitic decomposition products. The boundary between the Tokatea Hill Series ( and the 
andesites on the western slopes of the Tokatea section of the main range, as shown on the map, is an 
arbitrary one, but probably follows closely the Tokatea " Big Reef," as this large quartz-body marks 
the contact in both Maddern and Courthouse Creeks immediately to the south. On the western slopes 
of the range to the south of the main Tokatea Road, at an elevation of 1,000 ft., the argillites occur 
in the workings of the Pigmy Mine. This is probably the lowest elevation of the main exposure in 
a southerly direction. The bushed country lying between the headwaters of the Waverley and Omoho 
Creeks probably conceals the northern boundary between this series and the Moehau Series. Ex- 
tending down the eastern slopes of the main range, the Tokatea Hill Series forms the country incised 
by the Harataunga Stream and its tributary the Waverley, to a point near the junction of Waikoromiko 
Creek with the Harataunga Stream. 

At Kuaotmau the altered light-grey spotted rock (page 45), exposed in the creek to the west of 
Hosie's Saddle, Waitaia Ridge, appears to be referable to an inher of the Tokatea Hill Series in the 
grits and argillites of the Manaia Hill Series. 

The general distribution of these rocks has been described at some length, as all the payably auri- 
ferous veins yet discovered in sedimentary rocks of the subdivision, with the exception of those in 
the Kuaotunu Goldfield, occur in the Tokatea Hill Series. 

GENERAL STRUCTURE. 

The general structure of this series has already been outlined in connection with the whole 
sedimentary complex. The prevailing strike is generally somewhat to the west of north, but is 
occasionally almost at right angles to this direction. The dip is, in the main, to the westward, and 
varies from 30° to verticality. 

In the Tiki area certain sections disclose a gradually increasing inclination in passing eastward 
across the beds until the headwaters of the main branch of the Tiki Stream are reached, when the dip 
changes to the eastward ; this may be the crest of the main anticline, but the easterly extension of 
the strata is concealed by overlying volcanics. In the Tokatea Hill area the disposition of the beds is 



43 

seldom apparent, but a westerly dip is probably preserved for some distance cast of the mountain 
divide. 

No faults of any magnitude have been detected in the area covered by these rocks, though minor 
fractures, with slickensided walls and bands of friction breccias, are all indicative of differential move- 
ment. An imperfect cleavage, which is generally parallel to the bedding planes, has been developed 
in some of the argillites, but more often they break with an irregular fracture. 

An abundance of intrusive rocks, which will be described in another section of this chapter, charac- 
terizes every locality in which the rocks of the Tokatea Hill Series are developed. 

PETROLOGY. 

Introduction. — The rocks of the Tokatea Hill Series consist of dark-coloured argillites and grau- 
wackes, with interstratitied beds of volcanic material — both pyroclastics and lava-flows. The argillites 
and grauwackes represent the sediments derived from some ancient continental land-mass, while the 
igneous material is the product of contemporaneous volcanic activity. The igneous rocks and the 
rocks showing the many phases of lithological gradation between the pyroclastic igneous rocks and the 
ordinary sediments, afford Considerable varietv. The rocks of the series have been considered under the 
following headings : — 

(a.) Argillites and grauwackes. 
(6.) Acidic tuffs and tufaceous mudstones. 
(c.) Quartz sericite rocks (altered rhyolites '.). 
(d.) Contemporaneous rhyolites. 

{a.) Argillites <//«/ Grauwackes. — The argillites and grauwackes generally occur as thin-bedded alter- 
nating strata of dark-grey or almost black colour with sometimes a greenish, bluish, or brownish tinge. 
The rocks weather to a yellowish-white thin soil. The decomposition clays frequently assume brilliant 
purple and red hues, due to percolation of iron-solutions from neighbouring andesitic areas, and are then 
with difficulty distinguished from the andesitic-decomposition products. Cleavage in these rocks is 
absent or is only incipiently developed, and true slates are therefore not represented in the area. 

The grauwackes are mineralogicallv the same as the argillites, and differ from them only in the 
coarser nature of their clastic constituents. They consist, in the main, of fragmental quartz and feld- 
spathic material with a minor amount of decomposing ferro-mayuesian minerals, in a tine groundmass. 
In the vicinity of intrusions considerable induration, both of argillites and grauwackes. is noticeable, 
and the examination of some sections shows that minute shreds and scales of secondary biotite have 
been developed. 

These rocks occur more or less in all the areas where the series is developed. In the Tiki Creek they 
both overlie and underlie the quartz sericite rocks and the tuffs. The dark drossy argillites met with 
in the vicinity of the Tokatea " Big Reef," in the No. 7 level of the Royal Oak Mine, should here be 
mentioned; these are apparently higher in the sequence than the felsitic or rhvolitic tuffs to be later 
described, and probably owe their drossy, slickensided appearance to proximity to the " Big Reef." 

(b.) Acidic Tuffs and Tufaceous Mudstones. — Under this heading have been grouped interesting and 
peculiar types of rocks, the true nature of which remained undetermined for many years. They occur 
in constant and intimate association with the quartz sericite rocks (altered rhyolites ?), wherever the 
latter are developed. They are doubtless the fragmental equivalents of these, or closely similar acidic- 
flow rocks, and the transition types which would result from a mingling of the fine tuffs with 
the ordinary argillaceous and arenaceous sediments. All these rocks, which are in general much lighter 
in colour- than the argillites and grauwackes already described, are considerably altered and pyritised. 

One of the most typical tuffs of the series occurs in Waverley Creek, on the eastern side of Tokatea 
Hill. Megascopically it is a compact, greyish, highly pyritised rock, with numerous small lighter- 
coloured spots. Under the microscope the fine matrix consists of angular and subangular fragmentary 
quartz with feldspathic material and sericite. In this matrix, decomposition products, including 
calcite and sericite, occur as areas having more or less rectilinear boundaries suggesting altered feldspars. 
Quartz is present both as irregular-shaped grains, and as roughly bipyramidal individuals ; cubes and 
segregations of pyrite are common. Similar rocks are met with in the Tokatea Mine workings, also at 
the Tiki and in the Manaia Valley. 



44 

Some "t the most peculiar and frequently occurring rocks of the series are those which have in the 
petrographical monograph of Sollas and McKay* been termed respectively " spotted adinole," " spotted 
adinole or grauwacke,"' " spotted adinole or fine-grained grit," " grauwacke," " altered fragmental 
rock containing large fragments of a volcanic flow." 

These rocks, which have generally a felsitic appearance, vary in colour from a leek-green to greenish- 
grey, grey, and bluish-black. They are frequently mottled with rounded spots or arborescent patches, 
usually of greenish tint and darker than the general mass of the rock. These spots are usually small, 
but occasionally exceed an inch or an inch and a half in diameter. The rocks are in the main very 
fine-grained and compact, breaking with a subconchoida', or splintery fracture, and showing sharp edges 
which at times exhibit faint translucence. Platy jointing is not uncommon, and the joints often include 
patches or films of bright pyrite, which mineral, as fine grains and aggregates, also occurs generally 
throughout the rock. A parallel banding is occasionally noticeable. Less frequently the rocks are 
softer and lighter-coloured, and present a somewhat steatitic appearance. 

Under the microscope the matrix has a dusty granular or sometimes minutely crystalline appear- 
ance and frequently shows patchy extinction between crossed nicols. Scattered through this finer 
matrix is quartz as angular grains, splinters, and rarely rounded granules. Minute bipyramids of 
this mineral are also present. Plagioclase feldspar occurs as angular flakes, shreds, and rounded 
mains, the extinction angles, 15°/15°, indicating an acid type. Pseudomorphs of calcite and seriate 
after this mineral are not infrequent. Orthoclase has certainly been detected in the sections, 
but is considerably sericitised. Sericite, in part already mentioned in previous sentences, is, 
next to quartz, probably the most abundant mineral in these rocks, and with it is sometimes 
associated chlorite. A few worn flakes of muscovite, in addition to secondary muscovite, and 
ilmenite granules altering to leucoxene, have also been detected. Pyrite as cubes and grains, and 
as films lining fractures, is more or less conspicuous in all these rocks. The peculiar spots and 
rounded patches which sometimes simulate the andalusite growths in a spotted schist, are the result 
of secondary changes by which some new mineral has been sporadically developed throughout the 
matrix, but the mineral itself has not been determined. These spots are freer from granules than the 
general matrix of the rock. One of these rocks, the matrix of which includes small bipyramids of 
quartz, is of considerable interest as affording additional proofs of volcanic action contemporaneous 
with this period of sedimentation. Concerning these fragments Professor Sollas remarks : "Some(l) 
[are] fairly large, consisting of altered feldspar laths with trachytic habit in flow lines, spotted with 
patches of carbonates ; (2) others [are] composed of large isolated grains of quartz and large sericite 
pseudomorphs after feldspar. The coarse fragmentary material (2) is opposed to the notion that this 
is a flow rock with included xenoliths, and leads to the conclusion that it is fragmental but largely com- 
posed of fragments of flow rocks."f 

The analyses of four typical samples of these rocks are as follows : — 

Silica (Si0 2 ) 
Alumina (A1 2 3 ) 
Ferric oxide (Fe 2 3 ) 
Ferrous oxide (FeO) 
Manganous oxide (Mr>0) 
Lime (CaO) 
Magnesia (MgO) 
Potassium- oxide (K 2 0) 
Sodium-oxide (Na 2 0) 
Titanium- oxide (Ti0 2 ) 
Carbonic anhydride (C0 2 ) 
Water and organic matter 

Totals .. 100-22 10025 100-28 10015 

Locality.— No. 1, Tiki Creek; No. 2, Hauraki Associated Mine, Tokatea Hill; No. 3, Peveril Mine, 
south of Tokatea Saddle ; No. 4, No. 3 level, Royal Oak Mine, Tokatea Hill. 

* Sollas and McKay : " The Rocks of Cape Colville Peninsula," vol. i, 1905 ; vol. ii, 1906. 
t Loc. cit., vol. i, 1905, p. 186. 



1. 


2. 


3. 


4. 


60-75 


57-72 


58-40 


66-20 


18-34 


. 22-49 


1911 


20-51 


0-40 


0*96 


576 


084 


5-76 


4-82 


1-22 


112 


0-42 


0-31 


0-29 




2-60 


1-05 


2-95 


0-95 


2-03 


2-34 


2-84 


0-72 


2-92 


3-87 


2-59 


310 


1-69 


118 


2-80 


0-90 


0*51 


066 


0-72 


0-21 


1-50 


005 


1-84 


010 


3 30 


4-80 


1-76 


550 



PLATE VII. 



**' 



* 



♦ 

• ..m ■ 



■ 




9Fm 








m 



^ 



\ 



. 



X 








1 <1£K 



++?*?' 



« ■ 




Spotted Acinic Toff, oh Tofaceoos Mudstone, Tokatea Hill Series, No. 5 Level, Rotal Oak 

Mines, Coromandel. 

Magnification, 50 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Bull. No. ^.] 



[To face. p. 44. 



PLATE VIII. 




Altered Rhyolite (?), Tokatea Hill Series, Manaia River. 
Magnification, about 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Bull. No. lf.-\ 



[To face p. jS 



^w mM BT MM wwaCTwiBiwtmtttW) vmrnven 



45 

The term " adinole " was applied by Sollas to these rocks subject to subsequent chemical analyses 
showing the necessary soda-content. These analyses, however, do not warrant the applicability of the 
term. This petrologist also remarks, " If not an adinole it might perhaps be termed a ' grauwaoke,' 
though I scarcely think this is a quite appropriate name."* 

The petrographical determinations leave little doubt that pyroclastic material of an acidic type 
contributed largely to the formation of these rocks, but it is impossible to determine to what extent 
the original sediments have been affected by metasomatic processes. While no specific names have been 
applied to these rocks in this report, they have been grouped under the heading, "Acidic tuffs and 
tufaceous mudstones." They occur in every area where the Tokatea Hill Series is developed — Whai- 
wango Creek, Tokatea Hill belt (forming the country rock of most of the mines), Success Hill - Tiki 
area, and Manaia Valley. The characteristic spotted rocks of the series have also been detected in the 
small left-hand branch of the creel: draining the western Hank of the Waitaia Ridge in the vicinity 
of the Waitaia Mine, but to what extent they occur in the workings of this mine has not been 
determined. 

(c.) Quartz Sericite Rocks (Altered Rhyolites '.).— The quartz sericite rocks a re pinkish-grey and cream- 
coloured, with ochreous stainings. The ochre-coloured portions sometimes show an irregular banding. 
They are hue or medium coarse in texture, not very hard, and break with an irregular fracture. These 
rocks wherever met with are considerably altered, and none of their constituent minerals are recog- 
nisable megascopically. Under the microscope they are seen to consist in the main of quartz and seri- 
cite. The quartz, which is much the more abundant mineral, occurs as mosaics varying in fineness 
but never very coarse, also as more isolated irregular grains some of which have a rhyolitic appearance'. 
The sericite forms felt-like patches, the scales sometimes showing a radiate structure, and again occurs 
interstitial to the quartz grains. Some of the sericite-felt areas present more or less rectilinear bound- 
aries, and show parallel striatums between cross oicols; they may represent pscudomorphs of other 
minerals such as feldspar. Ferric hydrates form the ochreous patches which are conspicuous in the 
hand-specimens, and are probably due to the alteration of pyrite, which is still sparsely present. 
Some of the sections show a good deal of leucoxene and a few crystals of zircon. 

The quartz sericite rocks are characteristic of the Tokatea Hill Series and have greatest develop- 
ment between Cadman Creek and Tiki Creek, forming conspicuous bluffs in the higher country and at 
the fork of the Tiki and Pukewhau Creeks. Similar bluffs with talus at their basis occur in the' gorge 
of the Manaia Stream. 

A rock which appears to show a transition between these and the type to be next described, occurs 
in the vicinity of the abandoned Blackmore's .Mine on the Tiki Opitonui Road, and has a parallel in 
certain rocks occurring near the north end of the Monte Christo Mine, Tokatea Rill. 

The boundaries of the thick bands of this rock are less regular than the tufffl and tufaceous mud- 
stones which are always associated with them, and they are apparently altered rhyolitic flow rocks. 
Sollas, as the result of petrographical examination. Bays, " It is tempting to think of these rocks as 
altered rhyobtes."| 

(d.) Contemporaneous Rhyolites. — The rocks considered under this heading are white or cream- 
coloured and frequently show ochreous Btainings, while grey-coloured bands, suggesting fluxional 
structure, sometimes occur. The rocks are often porous, and show scattered grains of quartz, and 
drusy cavities. 

Under the microscope some of these rocks show a very finely granular crystalline groundmass, 
consisting of quartz and sericite with scattered granules. In this groundmass quartz, as irregular 
corroded grains, occurs as phenocrysts. These grains show liquid and vapour cavities, and sometimes 
present bipyramidal forms surrounded by a secondary growth of quartz. The forms of certain areas 
rich in sericite and other secondary products suggest the former presence of feldspar. Sections cut 
from the banded rocks show streaks of mosaic quartz of different degrees of fineness. Grains of quartz 

♦Sollas and McKay: "Rocks of Cape ColviUe Peninsula," vol. i, 1905, p. 151. 
t Iak. cit., vol. i, 1905, p. 137. 



46 

of rhyolitic habit, and sericitic areas also occur. Black dust in banded alignment is present, and certain 
opaque dust, in accumulations having circular outlines, suggests possible spherulitic structures. These 
rocks are undoubtedly silicified rhyolites. 

These rhyolites have their greatest development on the eastern slopes of the Tokatea section of 
the main range, associated with felsitic tuffs apparently as interstratified bands having a west-north- 
westerly strike, and dipping to the southward. Two of the best exposures occur in the gorge of the 
Harataunga Stream, one a little distance above and the other a little distance below the junction with 
this stream of the creek on which the Royal Oak battery is situated. Another has been exposed in 
the excavations for the Royal Oak compressor-station situated on the bank of the Harataunga Stream 
20 chains above its junction with Waikoromiko Creek. What is apparently one of these bands appears 
in the workings of the Monte Christo Mine on the same side of the main range at an elevation of some 
1,200 ft. Bands of these rocks also occur in the gorge of the Manaia Stream. 

The Moehau Series. 

general statement. 

The term " Moehau Series " has been assigned in this report to the argillites and grauwackes, 
which have their greatest development in the Moehau Range in the northern portion of the 
subdivision. The rocks of this series cover a larger area than those of any other series of sedimentary 
rocks in the subdivision. 

AGE AND CORRELATION. 

These rocks have so far afforded no palteontological evidence. Park refers to what he considers 
" indistinct coralline structure from the black shaly rocks at Stony Bay " on the eastern coast-line of 
the Moehau district, but states that " the remains are too obscure to fix the age of the rock."* 
During the course of the present survey rock-specimens showing structures having a general resem- 
blance to fragmentary corals were collected from the Stony Bay locality, but further examination 
did not favour these structures being regarded as of organic origin. 

Many of the previous writers on the geology of this area refer to the strong lithological resemblance 
which the rocks under consideration present to fossiliferous (Carboniferous) strata in the Maitai Valley, 
Nelson. The term " Maitai Series," implying a Lower Carboniferous age, has therefore frequentlv 
been applied to these rocks of the Hauraki Peninsula. 

Reference has already been made to the relationship of the Moehau Series to the Tokatea Hill 
Series, and both of these, until more definite age-evidence is available, may with propriety be designated 
Pre-Jurassic, as they underlie rocks of the Manaia Hill Series, which at the typical locality contain 
Jurassic fossils. 

GENERAL DISTRIBUTION. 

The rocks of the Moehau Series have, within the subdivision, their maximum development in the 
Moehau and Colville Survey Districts and in the vicinity of Cabbage Bay. 

The major area may be considered as that portion of the peninsula lying to the west and north- 
west of a line drawn from the western coast-line at the mouth of Kairaumati Creek (Cabbage Bay) 
north-east for a mile and a half, and thence in a general direction north 26° west to the south headland 
of Stony Bay on the eastern coast-line. 

Within this area intrusive rocks and a few small patches of younger sedimentaries and effusive 
volcanic rocks also occur. 

Continuous with the main area just described is a belt half a mile to one mile and a quarter in 
width, extending in a southerly direction from the Kairaumati Creek for a distance of four miles 
up the main vallev of the Umangawha Stream, which drains into Cabbage Bay. Westward of the 
mouth of the Umangawha and its flood-plains these rocks again appear for a distance of some 40 chains 
on the southern shores of Cabbage Bay, and are here overlain by the breccias and agglomerates of the 



* " The Geology and Veins of the Hauraki Goldfields " (J. Park), 1897, p. 15. 



47 

Beeson's Island Series. The rocks of the Umangawha Valley attain their greatest elevation (800 ft.) 
in Sutton Creek, one of the south-easterly branches of the main stream. 

On the eastern side of the main divide, distant 60 chains from the Sutton Creek outcrop and at 
a nearly corresponding elevation, similar rocks are exposed in the headwater branches of the Omoho 
Creek; these further south give place to the Tokatea Hill Series, the ((intact being obscured by heavy 
surface debris. 

Certain rocks in the Mangatu and Mataiterangi Creeks (Kennedy's Bay Valley) may belong to this 
series, but more resemble the Manaia Hill Series with which they have been correlated. Reference 
has also been made to the possible occurrence of minor areas of the Moehau Series involved with the 
Jurassic sediments in the lower portions of the Waiau and Matawai Valleys. 

GENERAL STRUCTURE. 

The disposition of the strata as a whole in the main Moehau - Cabbage Bay area, where these 
rocks have their greatest development, is difficult to determine owing to the local deformations which 
the beds have frequently undergone as the result of numerous igneous intrusions. More especially 
is this true of that portion of the area lying to the westward of Moehau Ranee. Throughout the 
whole of this area the beds would appear to preserve a general strike varying from a few degrees 
east to a few decrees west of the meridional line and a prevailing dip to the westward, though consider- 
able local irregularities occur in the outcrops observed on the western side of the mountain divide between 
Hope Creek and Port Jackson. The only marked exception to the prevailing westerly dip appears 
on the northern coast-line just westward of Sugar Loaf Rocks. In this locality the strata, for a distance 
of 20 chains, dip regularly at fairly low angles to the eastward, the minor anticline and svncline produced 
by the flexure having a pitch to the northward. A boss of intrusive rock, which denudation has not 
yet exposed, may possibly account for this minor irregularity. Transverse to the prevailing 
strike, the beds extend over a distance of five miles, and the average westerly dip is about 50°. An 
isoclinal folding of the strata can hardly be assumed to account for the great thickness of sediments 
which apparently exists here, as the angles of inclination are frequently low : moreover, no metamorphism 
of the rock is apparent apart from that locally effected by the intrusives. Strike faults might be 
assumed to partly account for the persistent westerly dip, but such faults of any considerable 
magnitude, if they do exist, have not been detected. The whole exposure is probably the westerly limb 
of the main anticlinal fold, to which reference has been made in the opening section of this chapter. 

The strata are iu general thin-bedded, the argillite-. and grauwackes often occurring in rapid alter- 
nation. Zones showing the effect of crushing and movement are in places noticeable. The yielding 
of the layers of argillite has given rise to crumbling slickensided fragments, while in the harder grau- 
wacke numerous joints and fractures have resulted, causing the rock to break into small cuboidal or 
rectangular fragments. A recementing of these grauwacke fragments by siliceous material has in 
places formed friction or crushed breccias. 

Sharply marked fault-lines are not uncommon, but those observed are only of minor magnitude. 

The uumerous intrusions of diorite, porphyrite, and andesite, which occur as dykes and sheets 
in the rocks of the Moehau Series, will be specially considered in a subsequent chapter. 

PKTROLOGY. 

Preliminary Statement. — The sedimentary rocks forming the series under review show a marked 
uniformity throughout their whole areal extent. They exhibit little variety, consisting as already 
indicated of argillites and grauwackes with the usual lithological gradations between these two more or 
less definite types. Friction breccias are only of local occurrence, marking zones of crushing and rock- 
movement. The argillites and grauwackes at and near the contacts of the larger intrusive masses 
frequently show the effects of thermal metamorphism, hut beyond the influence of these intrusives, 
no metamorphic alteration is apparent. 

The Argillites. — The argillites are black or greyish-black in colour, and less frequently bluish or 
yellowish grey. The weathered rocks generally assume a yellowish-brown or buff colour, and along 
joints and bands where all the iron-compounds have been leached out a white powdery mass often 



48 

results. Segregations of the rusty-coloured hydrous ferric oxides frequently form veinlets ramifying in 
all directions. The fresh rocks are well compacted, occasionally show lamination, and are in general 
uncleaved. 

Under the microscope, clastic quartz and plagioclase feldspar are recognisable with fine interstitia. 
material, which was not resolved even under high magnifications. Fine mosaics of secondary quartz 
with some sericite, or again irregular calciferous patches and veinlets, are not uncommon. Some of 
the sections showed fine dark dust arranged apparently along planes of shearing. 

The argillites in the vicinity of many of the igneous intrusions have been considerably baked and 
indurated, and in many cases appear to have been subjected to silicification. Some of the very fine- 
textured siliceous rocks closely resemble lydian-stone. Cherty argillites, however, occur as narrow 
beds in areas showing no intrusive rocks, and these are apparently in part chemical precipitates. 

The Grauwackes. — The grauwackes differ mineralogically from the argillites only in the coarser 
nature of a great part of their clastic constituents, and in that, being less dense, they are generally some- 
what lighter in colour. Under the microscope the sections cut show subangular and rounded quartz 
grains, sometimes with fluid inclusions in alignment ; plagioclase feldspars with remains of albite twin- 
ning, extinction angle 19°/22° ; occasional small bent plates of biotite and muscovite ; also a fragmentary 
crystal or two of pyroxene and zircon. Ilmenite altering to leucoxene sometimes occurs, also dark, 
finely-comminuted magnetite. Secondary chlorite and sericite are present throughout the finer ground- 
mass. As in the argillites quartz or calcite forms fine ramifying veinlets or irregular patches. The 
mineralogical composition of these rocks suggests that the detrital material of which they are composed 
has been derived largely from the erosion of an area of crystalline rocks. 

Specimens of a grauwacke selected from within one of the aureoles of contact metamorphism show a 
considerable development of secondary biotite as small ragged laths and irregular scales fairly uniformly 
distributed throughout the rock, and with the long axes of the individuals showing a general alignment. 
Muscovite, epidote, and chlorite are also present, but to a much lesser extent. 

The Manaia Hill Series. 

general statement. 

The rocks of the Manaia Hill Series form non-continuous belts on each side of the mountain 
divide. They consist of fine conglomerates, grits, grauwackes, and shaly argillites, and present a 
marked uniformity in mineralogical composition wherever encountered in the subdivision. The 
series is named from Manaia Hill situated between the Coromandel and Manaia Harbours, a locality 
where the rocks are typically developed, and where they have yielded most of the identifiable fossils 
described. 

AGE AND CORRELATION. 

The rocks of the Manaia Hill Series have been involved with those of the Moehau and Tokatea 
Hill Series in great earth-movements. The general distribution of the Manaia Hill rocks as belts 
forming the lower flanks of each side of the mountain divide, is significant. This would imply their 
superposition on the rocks of the two older series, either on the assumption that the strata forming 
the range are disposed in the main with anticlinal arrangement, or that the sediments which formed 
the Manaia Hill rocks were deposited on each side of a ridge of land consisting of Tokatea Hill and 
Moehau rocks. The former is the more feasible hypothesis. 

The relationship of the Manaia Hill Series to the Tokatea Hill and Moehau Series has been considered 
in earlier sections of this chapter. In correlating the various isolated areas on both sides of the peninsula 
with the undoubted Jurassic strata of the Manaia Hill, the writers have relied almost entirely upon the 
physical and mineralogical character of the rocks. At Tawhetarangi, twelve miles north of Manaia, 
there was discovered in the fine conglomerates a small fragment of the prismatic layer of a bivalve 
shell(?) agreeing in structure with similar m?„terial from Manaia Hill. This discovery affords con- 
siderable support to the deductions based on physical and mineralogical data. 

The widespread occurrence of fine conglomerates and grits is evidence of sedimentation in com- 
paratively shallow water. Igneous material has contributed very largely to these sediments. Part 



PLATE IX. 




INOCEBAMUS HAAST1 (HoCHSTETTEll), FROM CONGLOMERATE, M\N\|\ llli.l. SERIES, MANAIA HlLL. 
Magnification, :( diameters. Work of Mr. Alexandei McKay, I'd s. 




M MS 



Belemnites Si'. (Transverse Section), prom Conglomerate, Manaia Hill Series, Max.ua Hill. 



Oeol. Bull. No. .',. 



[To face p. J,8. 



mmmmmmfmx 



49 

of this igneous material consists of fine detritus, with occasionally rounded pebbles exceeding an inch 
in diameter derived from diorites and porphyrites, but more remarkable is the very large part which 
flow andesites and flow rhyolites have taken in the formation of all these grits and conglomerates. It 
is difficult to speculate as to the source of this great amount of volcanic material, but the following- 
facts appear to bear on the question. The Tokatea Hill Series has been shown to contain interstratified 
rhyolites, and is largely intruded by numerous dykes of porphyrite and diorite. In this connection it 
is significant to note that intrusions occur much less frequently in the Manaia Hill Series than in the 
Tokatea Hill and Moehau Series ; moreover, those that do occur are less crystalline than mosl of those 
in the older rocks, and are probably of Tertiary age. It would appear, therefore, that the sediments 
which formed the Manaia Hill Series may have been derived from a land-mass consisting of rocks 
equivalent in age and lithological character to those of the Tokatea Hill and Moehau Series ; whilst the 
great sheets of andesitic lavas which must have existed, have probably as their hvpahvssal analogues 
some of the diorite and porphyrite intrusives of the existing areas of these Pre-Jurassic rocks. 

Fossils were discovered during the course of the present survey in these rocks at .Manaia Hill and 
at Tawhetarangi. At Manaia Hill the fossils were collected from the tine conglomerates of the road 
quarry, situated on the north-west side of the main Thames Coromandel Road, at an elevation ol 
325 ft., on the fall of the hill to Manaia Harbour. The fragmentary fossil from Tawhetarangi was 
obtained from a conglomerate band occurring within the tide-marks 7 chains south of the mouth of 
Tawhetarangi Creek. 

The fossils were submitted to Professor A. 1*. W. Thomas, of the University College, Auckland, for 
identification and description. His report, which follows in extenso, establishes the fact that the 
strata are not older than Jurassic, and are approximately of the same age as the Putataka beds 
of the New Zealand sequence — Upper Jurassic(')- 

Report on the Fossils of the Manaia Hill Beds (Cowmandcl). 
By Professor A. P. W. Thomas, M.A., F.L.S., F.G.S. 

The fossils received for examination were contained in thirteen fragments of conglomerate, 
twelve of these being from Manaia Hill and the remaining one from Tawhetarangi. The pebbles 
of the conglomerate are of quartzose and other hard rocks, whilst the matrix itself is very hard 
and of irregular fracture, so that it is very unfavourable for the extraction of the fossils. 
The fossils consist of : — 

(a.) Two casts of fragments of Inoceramus. 
(b.) Half a dozen fragments of Belemnite guards. 

(c.) Fragments of calcite in regular parallel prismatic fibres, probably portions of the 

prismatic layer of a bivalve shell. This fossil occurred in the single specimen from 

Tawhetarangi, agreeing in structure with similar material from Manaia Hill. 

In addition, one piece of the conglomerate included a calcareous fragment with markings which 

might be suggestive of a shell. There is reason' to believe, however, that this specimen is not of 

organic origin. 

Inoceramus Haasti, Hochstetter. 

Hochstetter. " Neuseeland," p. 190. 

Zittel. " Novara-Expedition," Geologiscber Theil, bandi, abth. 2, p. 33, tafel viii, fig. 5, a, b, c. 

The Inoceramus appears to belong to this species. It is represented by casts of two frag- 
ments. One fragment, however, is of considerable size, and reproduces the coarse concentric 
rugae and curvatures of /. Haasti in so characteristic a manner that I have little doubt that the 
identification is correct. An identification from such material cannot, however, be regarded as 
completely satisfactory, and must be held to be provisional. 

This species was first found by Hochstetter in strata of sandstone and conglomerate near 
Takatahi, on the south side of the Kawhia Harbour. 

Belemnites sp. 

The fragments of Belemnite guard were firmly cemented in a hard matrix, which could not be 
detached from the softer Belemnite. Hence the characters have to be deduced from the weathered 
surfaces or from cut and polished sections. The fragments had evidently been rolled and subject 
to injuries on their surface before being buried, whilst some of the specimens have clearly been 
broken by the compression of the neighbouring pebbles. Nevertheless, some good cross-sections 
were obtained, showing the usual radially fibrous structure of a Bslemnite guard, whilst the 
1— Coromandel. 



50 

concentric lines of growth are numerous and conspicuous, as many as seventeen being counted 
along a radius of 6 mm. The cross-sections are usually circular, with central axis of growth ; one 
section is very slightly oval. 

The most perfect specimen is about 25 mm. in extreme length and 12 mm. to 13 mm. in 
diameter. The smallest section is 4 mm. only in diameter ; others are of intermediate size. So far 
as these specimens can decide, the species did not attain a large size. 

By combining the characters seen in the different fragments, which seem to have belonged to 
one species, we may infer that the guard was of generally cylindric form, possibly becoming slightly 
compressed towards the alveolus. None of the fragments, however, actually show the alveolus. 

It would probably be difficult to absolutely fix the specific identity of a Belemnite from such 
data as are here afforded. Nevertheless, I have been struck with the similarity of the sections 
with those of an undescribed species of Belemnite which I have collected around the Kawhia 
Harbour and in the country north of the Baglan Harbour. The number of species of Belemnites 
recorded from the North Island is exceedingly limited, indeed the only one hitherto described is 
Belemnites Aucklandicus , Hauer." The undescribed species referred to is in some localities asso- 
ciated with with Belemnites Aucklandicus. It is distinguished by a rather fusiform guard, cylin- 
drical for the distal half of its length, but becoming gradually compressed laterally, as the alveolus 
is approached. The cross-sections are therefore circular at first, whilst those across the alveolus 
are strongly ovate. The narrow but rather deep ventral canal is confined to the alveolar end ; the 
lines of growth are very numerous and distinct. The specimens may reach 3 in. or 4 in. in length ; 
the thickness of the guard in the largest specimens is about 12 mm. The species is therefore quite 
distinct from B. Aucklandicus, in which the ventral canal is rather broad, and reaches almost to 
the point of the guard, whilst the growth-lines are few. It appears to me that it is highly probable 
that the Manaia belemnites belong to this second species from the Putataka beds, or at any rate 
to a closely similar species. 

If the above identifications be correct, it follows that the Manaia beds are of approximately the 
age of the Putataka beds, in which Inoceramus Haasti and the belemnite referred to are found. 
Hochstetter was in doubt as to whether these strata were of Lower Cretaceous or Jurassic age. 
In the map of the country around Kawhia Harbour, published by Hochstetter, the strata are 
described as probably Neocomian, but the fossils were described by Hauer as Jurassic. Zittel 
observes,! in summing up the discussion of the age of the beds, that the distinctly Jurassic 
character of Belemnites Aucklandicus, and the occurrence of Aucella plicata and Placunopsis 
striatula, favour the reference of the beds to the Jurassic system, although Inoceramus Haasti and 
Ammonites Novo-zealandicus have more likeness to Cretaceous species. It may be added that 
a species of Actinoceramus, a characteristic Cretaceous genus, is associated with B. Aucklandicus 
at the Waikato Heads. 

The Putataka beds would seem, therefore, to be of mixed palaeontological character, as 
compared with European strata. They have been generally described as Jurassic since Hoch- 
stetter's time. According to Sir James Hector^ they contain Middle Oolite fossils. Only when 
the Mesozoic fossils of New Zealand have been systematically studied and described shall we be 
able to fix the precise homotaxial position of the Putataka beds. 

For the present we may speak of the Putataka beds, and, if the above identifications be correct, 
of the Manaia conglomerates also, as belonging to the Upper Jurassic. 

DISTRIBUTION. 

The rocks of the Manaia Hill Series, as already indicated, form belts on each side of the 
main mountain divide. These belts are generally confined to the hilly country in the vicinity 
of the coast-line, and to the lower flanks of the main range. On the western side of the peninsula the 
most northerly area consisting of these beds is that which extends southward from a point on the coast- 
line near Tutahoa Creek to the valley of Paparoa Creek. In the lower and middle courses of the Waiau 
River, these rocks are again exposed and are continuous eastward into the valley of the Matawai and 
across Pukewhau Saddle to the source of Pukewhau Creek. 

In the Awakanae Creek they are seen to overlie the andesites of its lower reaches and are again 
exposed as an inlier in the creek-bed at an elevation of 380 ft. The largest continuous area of these 
rocks extends from Mill Creek on the south shore of Coromandel Harbour to Manaia Hill and into the 
valley of the Manaia Stream and its tributaries. The western boundary of the area follows fairly closely 
the Thames-Coromandel Road between the Coromandel and Manaia Harbours. 

* "Novara-Expedition," Geol. Theil, bd. i, abth. 2, p. 29. 
t " Novara-Expedition," Geol. Th. bd. i., abth. 2, p. 21. 
f " Outlines of the Geology of New Zealand," p. 67. 



51 

On the eastern side of 4he peninsula the most northerly exposure of these rocks occurs in the right 
headwater branch of the Waikawau Creek, and very probably attains to the crest of the main divide 
in the low depression which exists in this locality. A mile further south they form a small inlier in the 
bed of Cousin Jack Creek. The conglomerates and grits characteristic of the series are again exposed 
on the north and south shores of Kennedy's Bay, and for a distance of two miles northward up the 
valley of the Whareroa Creek, which drains into this bay. The sedimentary rocks exposed in the 
Mangatu and Mataiterangi Creeks are doubtfully correlated with this series. 

The Manaia Hill rocks again occur on the Kuaotunu Peninsula, being exposed at intervals on the 
coast-line for a distance of about a mile and a quarter to the north-east and a mile and three-quarters 
to the west of the mouth of the Kuaotunu Stream. Southward from the coast-line they extend up the 
valley of the stream, attaining on the Kuaotunu Mercury Bay Road an elevation of 4(50 ft., and further 
eastward form the main Waitaia Ridge, with a maximum elevation of 1,032 ft. These Manaia Hill 
rocks of the Kuaotunu area probably overlie strata of the Tokatea Hill Series in the vicinity of the 
Waitaia Mine on the western side of this ridge ; the boundary of the two series, however, owing to 
the great silicification and alteration of the sedimentary rocks, has not been determined. 

It is quite possible that small areas of these rocks, other than those mapped, may exist within 
the limits of the subdivision, as the finer-grained sediments are in the field almost indistinguishable 
from some of those of the older series. 

STRUCTURE. 

The rocks of the Manaia Hill Series appear to form in the main the lower portions of the 
eastern and western limbs of a north-and-south-trendine, anticline. The lowest depression in the 
main range, near the headwaters of the Waikawau Creek, appears to be the only point where these 
rocks attain to the actual crest of the water-divide, a fact which may imply that a depression existed 
in this locality even in Jurassic times. The strata on the westward side of the peninsula show a pre- 
vailing dip to the westward or south-westward, while on the eastern side of the peninsula easterly dips 
apparently predominate. Subsidiary flexures appear to lie present, hut the irregularity of the folding 
renders it difficult to decipher the structure from tli I isolated exposures of the series. 

Faults of any considerable magnitude have not been detected. It will be noticed from an inspec- 
tion of the maps accompanying this bulletin, that the beds of this series are much less frequently in- 
truded by igneous rocks than those of the two older series. This fact becomes very apparent where 
areas of the Manaia Hill and Tokatea Series occur in close proximity. 

PETROLOGY. 

Preliminary Statement. — As already remarked, the Manaia Hill Series consists of conglomerates, 
Lints, grauwackes, and argillites. all of which when examined under the microscope show a wonderful 
uniformity in mineralogical composition. The strata are well consolidated and indurated, but show 
no metamorphic alteration except in so far as they have been locally affected by the few dyke rocks 
which intersect them. 

Conglomerates. — The rock here classed as conglomerate is the one of most frequent occurrence 
in the Manaia Hill Series. It consists megascopically of a greyish-black gritty matrix, throughout 
which are interspersed numerous isolated lenticular and rounded fragments of a black siliceous slaty 
material. The rock is well consolidated. These slaty fragments in the most common rock-type 
seldom exceed \ in. in their greatest dimensions, and constitute relatively to the matrix only a minor 
proportion of the rock. Much less frequently the angular and rounded slaty fragments are of greater 
dimensions than that specified, and their total bulk exceeds that of the matrix ; the rock in this case 
generally assumes a dirty greenish-black colour. 

Sollas examined sections made from several of the rocks occurring in the road quarrv on Manaia 
Hill, and the general description is so applicable to the sections made from the many rocks collected 
by the writers, from widely separate localities within the subdivision, that this description is here quoted 
in ertenso : " The rock consists almost entirely of worn and fragmentary material, with scarcely any 
interstitial cement. Pebbles of various kinds and all sizes occur, from those visible without a lens 
4*— Coromandel. 



52 

down to others of microscopic dimensions. The interstices between the larger are filled with the smaller, 
and those between the smaller by others smaller still, and so on. Interstices unoccupied by fragments 
i^o thus rare, secondarily deposited material, such as carbonate and chlorite, occurring only in very 
insignificant quantity." * 

The pebbles consist of — (a.) A dark-brown fine-grained grit or graawacke, derived from older 
sedimentary rocks, with less frequently fragments of a calcareous grit, (o.) Andesites of several varieties, 
both micropcecilitic and hyalopilitic ; dacite ; the groundmass of flow rocks without phenocrysts. Most 
of these show marked fluxional structure, (c.) Rhyolites, generally silicified, some with traces of 
spherulitic structure, others showing banding with mosaic groundmass. (d.) Quartz, sometimes as 
bipyramids, again as large grains often containing liquid cavities ; plagioclase, as broken crvstals with 
bent or broken twinning lamellse, showing extinction angles of 10°/lo° ; fragments of micropegmatite ; 
small zircons ; calcite occasionally as pseudomorphs after some other mineral. 

These fine conglomerates, which consist so largely of the pebbles of igneous rocks, occur with 
remarkable persistency throughout all the areas of the subdivision mapped as Jurassic by the present 
survey. They are sometimes interstratified with their finer-grained equivalents — grits, grauwackes, 
and shaly argillites — or again they present a massive appearance. On account of the great amount of 
igneous detritus present, the rocks exhibit, on weathered surfaces, a white-speckled, tuff-like appear- 
ance. 

Bands which may best be described as pebble-beds are frequently found associated with the well- 
consolidated conglomerates, or again occur interstratified with the grauwackes and shales. The 
pebbles in these interstratified bands are generally well rounded, are cemented by a very minor amount 
of interstitial material, and range up to 1J in. in their greatest dimensions. They consist largely of 
grauwacke or siliceous slate, but igneous rocks — diorites, porphyrites, andesites, and rhyolites — are not 
uncommon. These beds are well exhibited on the coast-line between Tawhetarangi and Paparoa, also 
at Manaia Hill and in many places on the eastern side of the mountain divide where the rocks of this 
series are developed. 

The Grits and the Grauwackes. — The grits and the grauwackes differ from one another only in the 
coarseness or fineness of their rock or mineral constituents. Neither class differs mineralogically in any 
respect from the fine conglomerates already described, and there exists every phase of gradation be- 
tween the grits and these conglomerates. These rocks are of general occurrence, and may be specially 
mentioned as constituting at Tiki Hill and Kuaotunu the country rock of several of the mines. 

The Argillites. — The argillites are black, yellowish-brown, chocolate, brick-red, or purple-coloured 
shaly rocks, which occur interbedded with the coarser sedimentaries and are mineralogically the finer- 
grained equivalents of these rocks. They are of very general occurrence. An interesting phase of these 
rocks is the bluish-brown foliated slickensided rock, which occurs in Waiau River about a mile and a 
half above the Matawai junction. Its peculiar almost schistose structure is evidently the result of 
pressure and shearing The brick-red or purplish-coloured shaly argillites are most conspicuous on the 
Pukewhau Saddle. The colours are due to iron in various stages of oxidation. 

The micro-photographs (Plates 10 to 17) well exhibit the lithologic identity of the fine con- 
glomerates collected from the various areas mapped as the Manaia Hill Series. 



*Solla.s and McKay: " Rocks of Cape Colville Peninsula," vol. i, 1905, p. 193. 



PLATE X. 




Conglomerate, consisting mostly of Pebbles ok [oneous Rocks, Man.ua Hill Series, Manaia 

Hill. 

Magnification, 50 diameters. Work of Mr. Alexander .McKay, F.G.S. 



Geo Bull. No. ',.] 



[To fare p. St 



PLATE XI. 




Conglomerate, consisting mostly of Pebbles of Igneous Ro< ks, Manaia Hill Series, Waiad 

RlVER. 

Magnification, about 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Bull. Xo. I] 



[To face p. 52. 



PLATE XII. 




Conglomerate, consisting mostly ok Pebbles of Igneous Rocks, Manaia Hill Series, Waiad 

River. 

Magnification, about 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Dull. Xo. 4.] 



[To face p. 52. 



TLATE XIII. 




Silicified Ai!i:.\ ix Conglomerate, Plate XII, Man via Hill Series, Waiau River. 

Magnification, about 100 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Bull. No. ^.] 



[To face n. 52. 



PLATE XIV. 




Conglomerate, consisting mostly of Pebbles ok Igneous Rocks, Manaia Bill Series, 

Upper Valley oe Waiau River. 

.Magnification, about 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Bull. No. I] 



[To face p. .i2. 



PLATE XV 




Conglomerate, consisting mostly of Pebbles of Igneous Rocks, Manaia Hill Series, 

Matawai Cheek. 

Magnification, abouf M diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Bull. No. I] 



[To face p. 52. 



PLATE XVI. 




Conglomerate, consisting mostli of Pebbles of Igneous Rocks, Manaia Hill Series, 

Try Fluke Mine, Koaotunu. 

Magnification, about 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



Gro. /?„//. .W>. .}.] 



[To fare j>. 52. 



PLATE XVII. 



J? 



I ~M 












r,l 













mKi 



A 







m 



7-* 



• r 



:> 









©*; 



*£fc 



•** .. 



Conglomerate, consisting mostly of Pebbles of Igneous Rocks, Manala Hill Series, 

Kennedy's Bay. 

Magnification, about '■'>'■'> diameters. Work of Mr. Alexander McKay F.G.S. 



Geo. Bull No. ^.] 



[To face p. >2. 



53 



CHAPTER VI. 



THE TOREHINE SERIES. 



Page Page 

Introduction .. .. .. ..53 Age. and Palaeontology .. .. .".4 

General Distribution .. .. .. i>3 Special Areas .. .. .. .. . r >."> 

General Structure .. .. . . .">4 

Introduction. 
The Torehine Series consists of two more or less distinct divisions : — 

(a.) (Older.) Flnviatilc and estuarine beds with coal-seams Conglomerates, sandstones, and shales, 

with coal-scams. 

(b.) (Younger.) Marine beds. . .. .. .. Marly sandstones, calcareous sand- 

stones, limestone. 

Mere isolated patches of these stratified rocks — a series which formerly must have covered a con- 
siderable area of the subdivision — now exist. The only fairly complete sequence of both the older and 
younger group of beds, is that exposed at Torehine. some three miles in a straight line south of Cabbage 
Bay, and from this locality the series has been named. 

Each of the other exposures shows only certain members of the series, and correlation of these 
particular beds with those of the typical locality is not always easy. 

The Torehine Series is the equivalent of the principal coal-bearing formation of New Zealand, and 
contains abundant fossils which are considered to indicate a bower Eocene(?) age for its beds. In the 
Coromandel subdivision the chief interest attaching to the series, apart from any economic value of its 
limestone and coal, is in connection with the stratigraphy of the peninsula. These beds lie uncon- 
formably between the folded and worn-down Jurassic and Pre-Jurassic sedimentaries, and the great 

pile of volcanics which constitutes, in the main, the auriferous rocks of the subdivision. The Tertiary 
age of the volcanics is thus demonstrated. 

I ; bnebal Distribution. 

The rocks of the Torehine Series occur as small isolated patches af several localities on both sides 
of the mountain divide. These are found at elevations varying from sea-level to 1,125 ft., and always 
overlie in marked unconformity the older rocks. 

This distribution and mode of occurrence indicate that there must have been a relatively long 
period of denudation of the Torehine Series and older rocks contemporaneous with and subsequent to 
the elevation of the former above sea-level, and prior to the extrusion of the earlier Tertiary volcanics. 

With the exception of two small patches, all the isolated areas covered by these rocks occur to the 
north of the southern boundary of the Harataunga Survey District. The most northerly exposure is 
that on the coast-line a mile and a half to the eastward of Cape Colville. The most extensive develop- 
ment of the beds is in the vicinity of Torehine. where they extend alone the western coast-line from 
Anthony Creek to Tawhetarangi Creek, and inland to near the headwaters of both these streams. The 
beds near the heads of these streams are overlain by the " Second Period " volcanics, but again appear 
further eastward in Branch Creek, a western tributary of the Dmangawha Stream flowing into Cabbage 
Bay. Within the I'mangawha Valley the strata of this series are also exposed in Sutton Creek, and in 
the excavated cuttings of the Austral Road. A small area of the coal-bearine portion of the scries 
occurs on the western flanks of Moehau Range between Waiaro and Neilson Creeks. On the eastern 
side of the peninsula, several small exposures are seen in the valley of the Omoho Creek which drains 
into Kennedy's Bay, and an isolated patch occurs near the head of Stewart Creek on the outer portion 
of the Kuaotunu Peninsula. 



54 

General Structure. 

The strata of the Torehine Series invariably overlie, in marked unconformity, the folded and 
denuded Jurassic and Pre-Jurassic sedimentaries. The broken and irregular surface of the older base- 
ment rocks, underlying at Torehine and elsewhere the series under review, is proof of deposition on a 
land-mass of comparatively rugged topography. The general character of the beds further suggests 
that they were deposited during a period of gradual depression, or positive movement of the strand. 
The maximum stage of depression resulted in the formation of a coralline limestone, containing a few 
foraminifera, which is evidence that marine conditions then prevailed over certain portions of the pre- 
sent peninsular area. 

Unlike all the older sedimentary rocks the strata of the Torehine Series are never disposed at very 
high angles. The beds of nearly all the widely separated exposures show a rather remarkable agreement 
in their strike and in the direction of their dip. The strike of the strata varies little from north-north- 
west, while the dip is to the east-north-east, though the angles show variation from almost 0° to 
45°. The occurrences on or near both the eastern and western coast-lines of the peninsula are little 
above the present sea-level, whereas those further inland attain elevations exceeding 1,100 ft. on the 
flanks of the main dividing range. 

The last great folding movement which has affected the area evidently postdated the formation of 
the Torehine Series, since the present position of these rocks cannot be accounted for by any simple tilting 
of strata. Although the rocks of the series considered are found directly overlain by volcanic rocks 
of both the " First " and " Second Periods," in only one instance has an intrusive been discovered 
actually intersecting them. This occurs in the lowest outcrop of the main Omoho Creek, and will be 
described later. 

Age and Palaeontology. 

At Torehine many of the carbonaceous shales of this series contain leaf-impressions, but these are 
rather too poorly preserved to admit of identification. At Waiaro, however, abundant well-preserved 
leaf -impressions are found in the hard coaly shales associated with the coal-seams. These were inves- 
tigated by Maclaren, who identified the following forms* : — 

Blechnum priscum (of Ettinghausen) (Alethopteris of Hector). 
Flabellaria sublongiraehis (Ettinghausen). 
Bambusites australis (Ettinghausen). 
Fagus sp. 

In the marine beds of Torehine, Branch Creek, and the head of the Umangawha Stream the follow- 
ing fossils have been reported by previous investigators — McKay (C.-9, 1897, pp. 48 and 49) ; Park 
(" Geology and Veins of the Hauraki Goldfields," 1897, p. 16) ; Maclaren (C.-9, 1900, pp. 12 
and 13) — to occur : — 

Protozoa : 

Foraminifera (McKay, Park, Maclaren). 

Ccelenterata : 

Small Bryozoan corals (McKay, Park). Variety, Flabellum (McKay). 

Echinodermata : 

Pentacrinus stdlatus (McKay, Park, Maclaren). 
Hemipatagus tuberculatus (McKay, Park). 

Mollusca : 

Cueullcea (McKay, Park). Cucullcea sp. (Maclaren). 

Ostrea wullerstorfii (McKay, Park, Maclaren). 

Cardium(l) (McKay). 

Venus (Park). 

Turritella (McKay, Park). 

♦Maclaren: C.-9, l'JOO. p. 13. 



55 

Turritdla gigantea (Maclaren). 

Fusus (McKay, Park). Fusus sp. (Maclaren). 

Vertebrata (Pisces) : 

Teeth of Lamna huttoni (Maclaren). 

McKay* refers the rocks constituting the Torehine Series of the present bulletin to a Cretaceo- 
Tertiary age, whereas Park claims for them a Lower Eocene age. 

Maclaren remarks as follows in connection with the leaf-impressions of the Waiaro beds, which 
apparently occur in the lowest horizon of the series : " On the whole the forms [described] resemble 
markedly the fossil flora of the Pakawau beds, Nelson Province. Von Ettinghausen very strongly 
insisted on a Cretaceous age for these Pakawau beds. . . . These land-fossils at Waiaro therefore 
contradict somewhat the evidence of the Torehine marine fossils, which are undoubtedly Lower Ter- 
tiary in age." The marine strata at Torehine, Maclaren refers to a Lower Eocene age. 

A considerable number of fossil forms, representative pf both the flora and the fauna of this series, 
were collected during the course of the present survey. Sonic of these forms have not previously been 
reported as existing here ; they have, however, not yet been identified. 

Pending the expert palseontological investigation necessary to settle authoritatively the question 
of the age of these particular horizons of the New Zealand sequence, the Torehine Series of the 
subdivision is assumed to be not later in age than Lower Eocene. 

SPBl iai. Akkas. 

Torehine. — In the vicinity oJ Torehine the beds of the series first appear on the coast-line about 
4 chains south-west of Anthony I Ireek, and passing southward from here occur over a total distance of 
55 chains (measured in a straight line). The most southerly outcrop is distant some 10 chains south 
of the mouth of Tawhetarangi Creek. The beds, for a distance along the coast -line ol some 15 chains 
from the most northerly outcrop, pass below aea-level ; but from here southward they are seen over- 
lying in marked unconformity the older sedimentaries. for the first H chains as a continuous capping, 
then as more or less isolated patches. This main exposure extends inland for about a mile, a sinuous 
line marking the eastern boundary of the series with the overlying volcanic breccias of the "Second 
Period." At the main junction of the Tawhetarangi Stream another small patch of the beds of the 
series is exposed. 

The strata where exposed on the coast-line at Torehine strike north 10 west, and dip to the east- 
north-east at angles approximating 15°. The sequence in ascending order is — 

1(1.) Conglomerates. 

((2.) Sandy shales with carbonaceous material. 

1(3.) Marly sandstone. 

(4.) Calcareous sandstone. 

(5.) Coralline limestone with foraminifera. 

(1.) The Conglomerates. — The conglomerates have a maximum thickness of 30 ft. to 40 ft., and 
consist of boulders of gratiwacke and argillite in a ferruginously stained arenaceous cement. The 
boulders are well rounded, and in the lower part of the bed they range up to four or five inches in 
diameter, while in the upper portion they are usually of smaller dimensions. These boulders are 
evidently of local origin, and no igneous rocks were discovered among them. The conglomerates 
attain their greatest thickness at Torehine Point, and small patches also occur some 16 chains to the 
north and 8 chains to the south of the mouth of Tawhetaran»i (reek. 

(2.) Sandy Shales with Carbonaceous Mutt-rial. — The sandy shahs generally overlie, but in places 
underlie, the conglomerate, and both were evidently being deposited contemporaneously. The shales 
enclose numerous dicotyledonous leaf-impressions, and also casts of small lamellibranchs and 
gasteropods. This is evidently the horizon in which coal should occur, but recent marine sand 
covers the junction of these beds with the main conglomerate band. A thin coaly parting, however, 
occurs in an outlier of these sandy shales a little further southward than Torehine Point. 



(a.) Fluviatile and estuarine 



* McKay: Sollas and M<K.ay: " Rocks of Cape Colville Peninsula," vol. i, 1905. i>. 43. 



56 



(3.) Marly Sandstone. — The marly sandstones have a greenish or purplish tinge, and grade imper- 
ceptibly into both the underlying sandy shales and the overlying calcareous sandstones. Most of the 
specimens of Ostrea wullerstorfii were collected from these sandstone beds near the coast-line, and at 
the main bifurcation of the south branch of Tawhetarangi Creek. The marly sandstones, especially 
in the vicinity of the overlying calcareous sandstone, contain concretions of a calcareous nature. 

(4.) Calcareous Sandstone. — This sandstone is of a brownish-grey colour and fairly coarse texture, 
and includes here and there a small rounded pebble of grauwacke. The bed is approximately 50 ft. 
in thickness, and the rock may be regarded as a transition between the marly sandstone and the lime- 
stone. Most of the fossil mollusca which characterize the series are found in this horizon. 

(5.) Coralline Limestone. — A limestone forms the highest visible bed in the series, and is exposed 
with a dip of 15° on the coast-line for a distance of 3 chains at right angles to strike, representing a 
thickness of about 50 ft. 

The limestone is hard, compact, semi-crystalline, and of brownish-grey colour, glistening with 
minute facets of calcite. Under the microscope (see Plate 19) it is seen to consist largely of bryozoan 
corals, among which foraminifera are sparsely scattered. 

The following is an analysis of a fair sample taken from various parts of the bed : — 

Per Cent. 
10-2 
30 



Silica (Si0 2 ) 
Iron-oxides and alumina 
Lime (CaO) 
Magnesia (MgO) 
Carbon-dioxide (C0 2 ) 
Undetermined 

Total 



48-8 
0-9 

36-9 
0-2 

1000 



There is no great area of this limestone exposed on the coast-line, and from the irregular contours 
of the old surface of the basement rocks upon which it rests it is doubtful how far it may extend inland. 
The fact, however, that it is the only limestone exposed on the coast-line within the limits of the Hauraki 
Gulf renders it of economic importance as a flux for metallurgical purposes. This limestone affords 
small characteristic outcrops in the valley of Anthony Creek about half a mile from the coast-hne. 

Branch Creek (Umanyawha Valley- Cabbage Bay). — Branch Creek is the principal westerly branch 
of the Umangawha Stream and incises the inland side of the coastal range, which on the opposite and 
seaward side is scored by Tawhetarangi and Anthony Creeks. Marine beds of the Torehine Series 
occur in Branch Creek at an elevation of about 700 ft., and doubtless the strata here and at Tawhetarangi 
are more or less continuous under the volcanic rocks which form the greater part of this coastal range. 
Neither the basement argillites and grauwackes nor the lower members of the Torehine Series are visible 
in this locality. Marly sandstones passing upwards into calcareous sandstones are the rocks exposed 
at the lower levels in the creek-bed. These are overlain by a semi-crystalline coralline limestone, similar 
to that at Torehine. 

Mr. D. V. Allen, who examined the area, reports that this limestone forms, at one point on the 
eastern side of the creek, a hill fully 100 ft. in height. An analysis of this limestone is as follows — 

Per Cent. 



Silica (Si0 2 ) 
Iron-oxide and alumina 
Lime (CaO) 
Magnesia (MgO) 
Carbon-dioxide (C0 2 ) 
Water and organic manner 



350 

230 
52 20 

080 
40-50 

0-70 



Total 



100-00 



The beds of the Torehine Series in Branch Creek strike north 30° west, dip to the north-east at 
angles approaching 35°, .and are exposed for a distance of 15 chains. 



PLATE XVIII 



i a, 




TOREHINB, SHOWING STRATA OF THE '" TOREHINE SERIES." 




Moehau Range, viewed from Tawhetarangi. 



Geo. Bull. X» ;.] 



[To face p. 56. 



PLATE XIX. 




Coralline Limestone, Torehine Series, Toreiiixe. 
Magnification, about 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



<:<■■- Bull. \o. l] 



[To face p. 6 



57 

Probably a larger area of limestone exists in Branch Creek than at Torehine, the limestone from , 
which would furnish a reliable source of supply for metallurgical or other purposes, but in order to 
afford means of transport to the seaboard at Cabbage Bay a tram-line over four miles in length would 
be required. 

Sutton Creek and Austral Road (Umangawha Valley). — At an elevation of about 900 ft. Sutton 
Creek, a branch of the Umangawha, crosses the Austral Road on the steep flanks of the main mountain 
divide. At this point, and for a distance of about 12 chains to the north-eastward, the sandy shales 
are found overlying the Pre-Jurassic sedimentaries. These shales, in places well laminated, enclose 
numerous reed-like plant-impressions and seams of carbonaceous material. 

Some prospecting for coal has been done in this locality, and a seam which is said at one place 
to have shown a width of oft. was located. Cox, who reported on this occurrence in 1881,* quotes 
the following analysis : — 

Per Cent 
Fixed carbon . . . . . . . . ..... . . 5902 

Hydrocarbon . . . . . . . . . . . . . . 2-69 

Water .. .. .. .. .. .. .. .. 2-31 

Ash .. .. .. .. .. .. .. .. 35-98 



Total .. .. .. .. 10000 

The high percentage of ash renders the coal of very poor quality, and the position and extent of 
the beds in which it occurs renders it certain that no seams of commercial importance can be expected 
to occur in this particular locality. 

Waiaro Area. — On the western Hank of the Moehau Range, at an elevation of 1,125 ft., an ex- 
posure of the lower division of the Torehine Series occurs on the spur between the valleys of Waiaro 
and Neilson Creeks. The beds, here resting on the rocks of the Ifoehau Series, strike nearly east and 

west, and dip to the northward at angles approaching 40 . They consist in the main of a considerable 
thickness of bluish-»rey shales, with which are interstratified coal-seams, carbonaceous bands, gritty 

sandstone, and thin bands of conglomerate. This conglomerate resembles the finer conglomerate 

of Torehine. but contain- small rounded pebbles of quartz. 

Some prospecting for coal has been carried on here. In a drive some 76 It. in Length a coal-seam 

has been intersected dipping about 40° to the northward. The carbonaceous formation is about 5 It. 

in thickness, but consists in the main of black coalv -hales which break along joint-planes into sheeted 

masses presenting bright graphitic surfaces. The leaf-impressions, to which reference has been made 

in the palaeontologies! section, were obtained from these shales. In the middle portion of this hand of 
black shales, thin seams of glistening, friable, anthracitic coal occur. An analysis of this coal is as 

follow 

J'er Cent. 

Fixed carbon . . .. . . . . .. .. . . 90-85 

Hydrocarbons .. .. .. .. .. .. .. 5-30 

Water .. .. .. .. .. .. .. .. 0-85 

Ash .. .. .. .. .. .. .. .. 3-00 



Total .. .. .. .. 10000 

Total sulphur. 1-4 percent. 

Tin- metamorphism of brown coal to it- present anthracitic state would seem to indicate the pre- 
sence of an igneous intrusion, hut no such intrusion is visible, BO that the phenomenon must be con- 
sidered as probably due to intense pressure accompanied by thrust movement along the coal-seams. 
The sheeted structure in the shale and the slickensided graphitic surfaces support this conclusion. 

Taking into consideration the locality of the occurrence and all local conditions, further prospecting 
for coal, notwithstanding its excellent quality, would not appear to be warranted. 

* Rep. G.8., vol. xiv. 1HS-2, p. 41. 



58 

Area near Cape Colville. — The beds forming the area occurring on the northern coast-line, 95 chains 
to the east of Cape Colville, are of the marine type. They consist, in ascending order, of — 

(a.) Shelly conglomerate (20 ft.), (highly fossiliferous). 
(b.) Marly sandstone (15 ft. to 20 ft.). 

(c.) Shelly conglomerate (2 ft. to 3 ft.), marly sandstone (10 ft.), shelly conglomerate (1 ft.). 
(d.) Sandstones and mudstones. 
The strata strike north 60° west, dip to the north-east at angles of 35° to 45°, and overlie a broken 
irregular surface of the Moehau rocks. 

Omoho Valley (Kennedy's Bay). — In the main valley of Omoho Creek and that of its southern branch 
the Mangakotukutuku, small isolated patches of the Torehine Series occur at elevations ranging from 
275 ft. to 550 ft. above sea-level. 

The beds represented here are the greenish-grey marly sandstones, and these, in the lowest ex- 
posure within the main creek, have instratified with them a band of very dark-coloured limestone, 
which is about 10 ft. thick. Immediately under the limestone is a thin calcareous layer crowded with 
Ostrea wullerstorfii . 

These remnants of the Torehine Series all lie directly on the old folded sedimentary rocks, and 
most of them appear to occupv depressions on the old surface. The coal-bearing division of the series 
is not represented in this locality. Rhyolitic tuffs and breccias, in continuity with the belt which ap- 
pears on the Cabbage Bay side of the main divide, here constitute the overlying rocks. 

An andesite dyke, intersecting both the old basement rocks and the beds of the Torehine Series, 
is well exhibited in the lowest exposure of the Omoho Creek bed. 

Stewart Creek (Kuaotunu Peninsula). — A small exposure widely separated from all those previously 
described is that found in Stewart Creek near the outer end of the Kuaotunu Peninsula. The beds 
here occur at an elevation of about 60 ft. above sea-level, and form an inlier in volcanic rocks of the 
Beeson's Island Series. The older sedimentaries or basement rocks are not exposed in the bed of this 
creek, but show on the coast-line near its mouth. The outcrop is to be correlated with the lower divi- 
sions of the Torehine Series, and consists of brown sandy shales and fine grits, with associated carbon- 
aceous bands. Coal occurs in these shales, but only as seams an inch or less in thickness. Shallow 
test-pits have been sunk at various points in the lower part of the valley without revealing any increase 
in the thickness of these seams. 



59 



CHAPTER VII. 



LOOSELY CONSOLIDATED AND UNCONSOLIDATED DEBRIS. 



Page Page 

Genera] Statement .. .. .. 59 Littoral Deposits .. . . tin 

Fluviatile Deposits .. .. .. 69 Talus and Wind-blown Deposits .. (il 

Lacustrine Deposits .. .. 6<i Earth-movements of Quaternary Times .. 61 

General Statement. 

Deposits consisting of loosely consolidated and unconsolidated debris do not cover a relatively 
great area of the subdivision. They are not deeply incised, and natural sections of other than the 

superficial portions are not obtainable. The greater bulk of these deposits occupy the floors and cm- 
bayments of the larger valleys, and rise with very gradual slopes towards the valley-flanks and the 
foothills of the ranges. Narrow belts also occur along the more exposed coast-lines extending from 
the littoral zone to the base of the elevated country. The maximum age of the debris is undeterminable, 
but in any particular locality the deposits are more recent than the youngest effusive rocks seen in 
that locality, and from the nature of the debris it has been considered as varying in age from Pre-Pleisto- 
cene to Recent. 

Fluviatile. lacustrine, and littoral deposits may be distinguished, together with accumulations of 
rock talus and wind-blown Bands. 

Ki.rvi a i ii. i Dkfosi re. 

The fluviatile deposits constitute the high level terraces and the more recent flood-plains of the 
various streams, as well as the gravel-beds, gravel-bars, and beaches of the actual watercourses. With 
these should also be included the fan deposits of certain high-grade streams. These deposits often 
coalesce one with another to form sloping strips of country skirting the ranges. 

All the high-level river-terrace-, worthy <>l note appear to be confined to the western side of the 
peninsula. These are rarely deeply channelled and, in general, merge insensibly into the more recent 
alluvium. The deposits consist of arenaceous ami argillaceous material, through which are scattered 
rounded andesitic boulders more or less decomposed, grauwacke and argillite boulders rather bitter 
preserved, and fragments of quartz, chalcedony, wood-opal, &c. 

In the vicinity of Coromandel Township high level terraces fringe the loot hills of the range, and 
in places attain elevations of 40 ft. or more. The largest of these extends from the left bank of 
the upper course of the Whangarahi Stream (sometimes known as Kapanjja Stream) to the right bank 
of the Karaka Stream, a distance of about a mile. Several high level terraces occur in the Waiau Valley 
near the locality where the stream enters the coastal flat. They here extend northward from the 
vicinity of the Tiki - Mercury Bay Road, to the flanks of the hills where the Tiki Creek (a tributary 
of the Waiau River) leaves its mountain course. Those portions of the terraces lying to the south 
of Tiki Creek have in the past attracted attention on account of their auriferous character, and the 
numerous old tunnels bear testimony to a great amount of prospecting. Sluicing operations in 
Sawmill Creek, which in its lower course cuts through these terraces, yielded a few payable returns 
from detrital gold and highly auriferous quartz boulders. The auriferous " wash " which occurred 
here is attributable to a reconcentration of the older terrace-gravels through the agency of the small 
stream. The auriferous quartz of these terraces has evidently been derived from the veins in the higher 
country, in the valleys of Pukewhau and Tiki Creeks, and possibly (judging by the occurrence of stibnite 
in the gravels) from the veins in the Matawai Valley. Terraces similar to these at the Waiau are 
found further south skirting the hills near the mouth of Awakanae Creek. The strip of sloping 



60 

alluvial country extending along the western base of Moehau is due partly to the union of the fans 
of the various high-grade streams scoring the flanks of the mountain-range, and partly to secular 
elevation of land. 

The modern fluviatile deposits constitute the flood-plains of the various streams, and occupy the 
floors and embayments of their valleys. These deposits consist of waterworn detritus derived from 
the older rocks of the area, and are disposed as rudely stratified, false-bedded gravels and sands. Near 
the sea-margin this fluviatile material coalesces with the deposits of the littoral zone to form alluvial 
flats. The largest of these flats occur in the vicinity of Mercury Bay and Coromandel, and others 
of lesser extent at Whangapoua, Kennedy's Bay, Cabbage Bay, Manaia, and elsewhere. 

Lacustrine Deposits. 

Evidence of the existence, in the subdivision, of lacustrine deposits during Quaternary times, 
has been afforded only by mine operations. The shaft of the Kathleen Mine, Coromandel, was sunk 
105 ft. through sands and muds before the andesitic rock was reached. The lower portion of this un- 
consolidated material, according to Maclaren, consisted of fine-grained blue and yellow clays containing 
leaf-impressions, and a shell of a Unio (Unio menziesii{l.), Gray).* It would appear, therefore, that 
at least temporary lacustrine conditions prevailed in this old valley during Quaternary times. 

Littoral Deposits. 

The littoral zone is the zone between high- and low-water marks. The deposits occurring here 
consist of boulders, gravels, sands, and estuarine muds, the last-named being more characteristic of the 
sheltered inlets and the estuaries. 

The older deposits coming under this heading consist of raised beaches and also certain estuarine 
deposits. The raised beaches, like the high-level river-terraces, are practically confined to the western 
side of the peninsula. 

Remnants of these raised beaches are conspicuous at several places on the coast-line between Ongahi 
Creek and Waiaro Creek. A short distance to the north of the latter locality they attain a maximum 
elevation of 70 ft. above the present sea-level. Their existence further southward, at Torehine, at 
an elevation of 80 ft. has been reported by McKay.f On the eastern coast-line the only occurrence 
observed was at Opito, on the north-eastern extremity of the Kuaotunu Peninsula. There is here 
a bench of well-stratified marine shingle lying 8 ft. above high-water mark. 

The older littoral or estuarine deposits are those at Coromandel, concerning which MaclarenJ 
makes the following reference : " A shaft through recent alluvium was sunk in 1862-63 at a point to 
the right of the Huaroa Creek, near the main Coromandel-Thames Road. It reached a depth of 150 ft. 
through varying beds of sands, clays, and gravels. At 150 ft. an old ' sea-floor with mangrove-stumps ' 
(in the words of the owner) was reached." 

It would appear that alluvium, to a depth of from 100 ft. to 200 ft., extends from a point north 
of the Kathleen shaft (see estuarine deposits) to the vicinity of the landward margin of the hilly andesitic 
outlier forming Preece's Point Peninsula. 

Littoral deposits, more recent in age than those described, form the beaches and mud-flats of the 
relatively great length of coast-line which girdles this portion of the Cape Colville Peninsula. Boulders 
and " shingle " are characteristic of the more exposed portions of the coast-line, especially those skirting 
areas in which massive igneous rocks abound. The extensive boulder beaches of the north-western 
shore-lines of the peninsula consist largely of the rocks which form the intrusives of Moehau Range. 
The set of the marine currents carries these well-rounded boulders even as far southward as Waiaro 
Creek, where they are piled up as great banks. A rougher coast-line is, however, that bordering an 
area in which heavy volcanic breccias and agglomerates predominate. The rough angular lava blocks, 
which constitute a great portion of these pyroclastic rocks, often stretch for miles along the seaboard 
between the tide-marks. 

* Maclaren: C.-9, 1000, p. 12. f McKay : C.-9, 1897, p. 70. J Maclaren : C.-9, 1900, p. 12. 



6 J 

Sandy beaches fringe the exposed coast-line where the country is of low elevation. The sand is 
generally light in colour, and consists in the main of quartz. A concentration-product is the thin layers 
of " black sand," consisting mainly of magnetite, which occur in some places on these beaches. This 
" black sand " in the regions of auriferous rocks carries a little gold, but this never occurs in sufficient 
quantity to be of any economic value. With the ordinary light-coloured sands is frequently associated 
an abundance of comminuted marine shells. The most extensive sand beaches are on the eastern 
side of the peninsula, where those of the following localities maybe mentioned: Cook's Bav(l| miles), 
Mercury Bay (Buffalo Beach, 2 miles), Mahinapua (2 miles), Whangapoua (2h miles), Te Pungapunga 
(1 mile), Kennedy's Bay (1^ miles), Matamataharakeke (1 mile), and Port Jackson (1 mile). 

The finer littoral deposits are the muds of the estuaries and other sheltered coastal inlets. On 
the eastern coast-line, muds with sandy lenses form the spacious tidal flats and the small islets of the 
upper portions of Whitianga Estuary, and also similar features of lesser extent in the Purangi Estuary. 
Extensive tidal mud-flats lie in the rear of the long sandy Omi 10 Spit which forms the outer barrier of the 
Whangapoua Harbour. The spit itself is the result of the conflict between marine and Huviatile forces, 
whereby sediments have been deposited as a bar. The inlets of the western coast-line of the peninsula 
— Coromandel, Te Kouina, and Manaia Harbours, and Cabbage Bay -exhibit spacious mudflats covered 
at high tide, but at low tide bare and incised by the narrow channels of the streams debouching into 
these iidets. Clumps of mangroves skirting the inner edges of these flats are not an uncommon feature, 
and assist in the reclamation of land, which in these localities is steadily progressing. 

Talus and Wind-blown Deposits. 

Talus-deposits occur on the slopes of some of the ridges, especially where these are bare or scantily 
covered with vegetation. This debris is largely due to the unequal expansion and contraction of the 
rocks attendant on alternate heating and cooling. 

Sand-dunes are conspicuous on portions of the northern and eastern coast-lines of the peninsula. 
This coast-line is exposed to the full force of the easterly and north-easterly winds which sweep the 
Pacific Ocean, and here, as might be expected, surf beaches are common. On the low grounds 
these sand-dunes are piled up to a height of from 10 ft. to 50 ft. Swamps, lagoons, and old stream- 
loops are of common occurrence in the rear of these lines of dunes. These features are to be observed 
at Port Jackson. Waikawau Bay, Whangapoua, Kuaotunu, Otama, Mahinapua, Cook's Bay, Wigmore 
Bay, and elsewhere. 

Earth-movements ok Quaternary Timi 

' onsiderable oscillations within Quaternary times are recorded in the distribution and vertical 
extent of the various deposits of debris considered in this chapter. A movement of depression, which 
probably took place in Pleistocene times, is indicated by the estuarine or littoral deposits which still 
exist at 120 ft. below the present sea-level in Coromandel on the western coast-line, and by the deep 
tidal estuaries extending far inland at Whitianga and Purangi on the opposite coast-line. This move- 
ment of depression was succeeded by a slow elevation of the land, especially along portions of the western 
shore. Old sea-beaches were here raised to the elevations at which their remnants are at present 
found, and the rivers were forced to excavate much of the alluvium they had deposited during the 
period of subsidence, thus giving rise to higher-level terraces along their banks. 



62 



CHAPTER VIII. 



IGNEOUS ROCKS 



Page 
Content . . . . . . 62 

(1.) Tertiary Volcanic Rocks of the " First 

Period" .. .. ..63 

General Statement . . 63 

Age .. .. .. ..63 

(A.) The Rhyolites .. ..64 

Distribution . . 64 

Structure, and Conditions of 

Eruption . . 64 

Petrology . . . . 64 

(B.) The Andesites and Dacites . . 65 
Distribution . . 65 

Structure, and Conditions of 

Eruption . . 65 

Petrology . . . . 67 

Megascopic Characters . . 67 
Structure of the Matrix . . 67 
General Character of the 

Phenocrysts . . 68 

Tvpes of the Semi-basic Rocks 
of the " First Period " . . 69 
(a.) Hypersthene Andesites 70 
(6.) Augite Andesites .. 71 
(c.) Pyroxene Andesites . . 71 
{d.) Hornblende Andesites 72 
(e.) Dacites .. ..73 

Propylitisation of the Volcanic Rocks 74 

(2.) Tertiary Volcanic Rocks of the " Second 

Period " (Beeson's Island Series) . . 75 

General Statement . . 75 

Age and Correlation . . 76 

Distribution . . . . 76 

Structure, and Conditions of Eruption 77 
Petrology .. .. ..80 

Megascopic Characters . . 80 
Character of the Matrix and Pheno- 
crysts . . . . N< I 

Types of the Volcanic Rocks of the 

" Second Period " . . 81 

(".) Hypersthene Andesites .. 81 

(b.) Pyroxene Andesites . . 82 



Page 



(2.) Tertiary Volcanic Rocks of "Second 


Period " — continued. 




Petrology — continued. 




Types of Volcanic Rocks of " Second 


Period " — continued. 




(c.) Hornblende Andesites 


83 


(d. ) Dacites . . 


83 


(3.) Tertiary Volcanic Rocks of the " Thirc 


I 


Period " 


83 


General Statement 


83 


Age 


84 


Distribution 


84 


Structure 


84 


Petrology 


85 


General Statement 


85 


Pumiceous Tuffs 


85 


Pumiceous Agglomerates 


85 


Pumiceous Breccias 


86 


Banded and Spherulitic Rhyolites. 


86 


(4.) Intrusive Rocks of Various Periods 


87 


General Statement 


87 


(a.) The Semi-basic Intrusives 


87 


Distribution 


87 


Age 


88 


Petrology 


89 


Quartz-biotite Diorite 


89 


Quartz Diorite 


90 


Diorite Porphyrite 


90 


Hornblende Porphvrito 


90 


Pyroxene Porphyrite 


92 


The Dacites 


92 


The Andesites 


92 


(/*. ) Acidic Intrusives — 


94 


General Statement 


94 


Distribution and Structure 


94 


Age 


94 


Petrology 


94 


(5). Succession of Lavas 


95 


(6). Igneous Rocks as Building-stones 


96 


Diorite 


96 


Pumiceous Tuffs and Breccias 


97 


Rock for Road- making 


97 



CONTENT. 
The igneous rocks described in this chapter comprise (a) a great pile of massive and pyroclastic 
volcanics. which were at different periods in the Tertiary era extruded upon a rugged denuded surface 
of older stratified rocks ; (b) intrusives — some of Tertiary age, which form dykes and sills in the several 
series of the basement sedimentaries, or which intersect the Tertiary volcanics ; others, probably refer- 
able to a Pre-Jurassic age, associated with the more ancient of the sedimentaries (the Tokatea Hill and 
Moehau Series). 

Certain contemporaneous volcanics have already been described as forming an important part 
of the Tokatea Hill Series, and to these particular igneous rocks no further reference need be made in 
the present chapter. 

The Tertiary vo'canic rocks range in chemical character from acidic to semi-basic, and are the 
products of three distinct periods of volcanic activity. The intrusive igneous rocks do not admit of 
definite separation according to age, and have therefore been grouped together. 



fi3 

The igneous rocks have thus been considered under the following headings : — 

(1.) Tertiary volcanic rocks of the " First Period." 

(2.) Tertiary volcanic rocks of the " Second Period " (Beeson's Island Series). 

(3.) Tertiary volcanic rocks of the " Third Period." 

(4.) Intrusive rocks of various periods. 

(1.) TERTIARY VOLCANIC RO< KS OF THE "FIRST PERIOD." 

General Statement. 

The Tertiary volcanic rocks of the " First Period " have greater areal extension and greater vertical 
range than the volcanics of either of the subsequent Tertiarv periods. The rocks of this series are in 
character semi-basic or intermediate, and to a very minor extent acidic. 

The acidic rocks, apparently the oldest of the series, are finely tufaceoua and brecciated rhyolites, 
which are confined to one belt, having but a very limited extension. 

The semi-basic rocks consist of andesitic and daeitic tuffs, breccias, agglomerates, and lavas, and 
are found comparatively fresh and in all stages of alteration and decomposition. The petrographical 
examination of numerous rock-sections of the less altered andesites and dacitea indicates that there 
exist only a few definite lithological types, and that in general these types are closely related to each 
other. As might be expected, minor phases of variation are of common occurrence even in the same 
lava-flow. None of the lavas show vesicular structure. 

There appears to be no distinct order of succession among the different semi -basic members of this 
great volcanic formation, and. owing to the absence of well-marked types and the persistent propylitic 
alteration and surface decomposition, it is difficult to establish the identity of a particular flow rock 
or of a breccia-bed even in two neighbouring areas. 

These volcanic rocks are piled up in mountainous masses, giving to the greater portion of the area 
its elevated and rugged character. The usual land-forms characteristic of crateral vents are. however, 
never preserved, owing to extensive modification by agencies of subaerial erosion. 

\i;e. 

The most direct and satisfactory evidence bearing on the age of the volcanic rocks of the 
"First Period" is afforded by the fact that they have been extruded upon a highly denuded 
surface of folded Jurassic and Pre- Jurassic sedimentaries, and, in certain localities, upon remnants 
of the Torehine Series of Lower Eocene(?) age. Further, these volcanics are themselves unconformably 
overlain by those of the "Second Period" which, upon the evidence available, have been referred 
to a Miocene age. It is therefore probable that the eruptions which gave origin to the volcanic rocks 
of the "First Period" continued intermittently throughout Upper Eocene times, and came to an end 
in the Lower Miocene period. 

The evidence is inconclusive as to whether or no the earliest Tertiarv eruptions in this suhdivison 
were those productive of the acidic rocks — rhyolites. These rocks, however, form a narrow belt which 
always directly overlies either the older sedimentaries. or certain isolated patches of the Torehine 
beds resting unconformably on these sedimentaries. They arc themselves overlain and intruded 
by the andesitic rocks of this locality, and are therefore of earlier origin than a great portion, if not all, 
of the semi-basic rocks. These rhyolites are much older than those which wilrbe later described as 
occurring in the south-eastern portion of the subdivision, or those which have considerable develop- 
ment on the plains in the neighbourhood of Waihi, beyond the limits of the area under review. 

It is of interest to note that McKay found on the higher slopes of Karangahake Mountain, in the 
southern portion of the Hauraki Division, spherulitic rhvolites which were intimately associated with 
the older Tertiary andesites.* 

These two occurrences at widely separated localities — Coromandel and Karangahake — may possibly 
represent contemporaneous extrusions, but the relationship of the rhyolites to the andesites at Karanga- 
hake has not been investigated. 



* •« Rocks of Cape Colville Peninsula," vol. i, 1905, p. 104 ; vol. ii, 1900, p. 35. 



64 



(A.) The Rhyolites. 

Distribution. — Rhyolites constitute only a small proportion of the volcanic rocks of the " First 
Period." They have their greatest development on the flanks of the main range, within the valley of 
the Umangawha Stream, which drains into Cabbage Bay. At a distance of one-quarter of a mile south 
of Trigonometrical Station BD, this belt of rhyolites crosses the main divide at an elevation of about 
1,700 ft., and further east appears in the valley of the Omoho Creek, which flows into Kennedy's Bay. 

Structure, and Conditions of Eruption. — The rhyolites forming the narrow belt already de- 
scribed, overlie directly the older stratified rocks and the remnants of the younger Torehine Series. 

The accumulation of the rhyolites under terrestrial conditions is evidenced by the mudstones 
with coaly partings, which are interposed between the basement beds of rhyolitic breccias and the 
Torehine strata in the Omoho Valley. These beds, constituting the lowest horizon of the rhyolitic 
effusives, are coarse breccias of rather dark colour, containing much shattered sedimentary rock and 
carbonaceous material, also occasional fragments of porphyritic dyke rocks. 

The rhyolites are in many localities considerably altered, but it would appear that the greater 
part, if not the whole, of these rocks is fragmental. The pyroclastic character of the material is well ex- 
hibited on the exposed cliffs of the western side of the mountain divide, in the vicinity of Barney Creek 
(Umangawha Valley). The bedded fine-grained tuffs, which are well consolidated, here dip at low 
angles to the south-west. With these tuffs certain bands occur which show, in addition to brecciation, 
wavy flowage-lines, and may therefore be designated " flow breccias." The rhyolites of this locality 
are overlain and intruded by the andesitic rocks forming the crest of the range. Andesitic dykes inter- 
secting the acid tuffs are also well exhibited in the lower gorge of the Omoho Creek. 

Petrology. — The rhyolitic tuffs are in general fine-grained rocks of pinkish-grey colour, showing 
small patches of cream-coloured waxy material derived from the decomposition of orthoclase, and also 
rounded grains or bipyramids of quartz. Small, dark-coloured, angular fragments of argillite and 
grauwacke, scattered through the rock, are relatively abundant. Under the microscope a matrix 
of light-brownish colour, generally micro-felsitic but in places almost glassy, is observed. Orthoclase 
is much the most abundant phenocryst, and occurs as fairly perfect crystals and as fragments all more 
or less sericitised. Plagioclase feldspar, although much altered, is recognisable by its twinning lamelhe. 
Quartz occurs as irregular rounded and angular grains, or as bipyramidal crystals, and biotite is occa- 
sionally visible as ragged plates. Ochreous patches occur sparingly throughout the groundmass of 
the rock, and are probably due to the decomposition of secondary pyrite. 

These tuffs occur in the Omoho Valley and at many localities in the Umangawha Valley. At the 
Rangatira Claim, about 20 chains west of Trigonometrical Station BD, the tuffs contain small black 
inclusions of pitchstone, otherwise they resemble those already described. Silicification and pyritisa- 
tion of the rocks is, however, particularly noticeable at the latter locality. 

An analysis of a sample of typical rhyolitic tuff from the Omoho Creek, which, however, unavoidablv 
contains small inclusions of argillite. is as under 

69-30 
13-92 



Silica (Si0 2 ) 
Alumina (A1 2 3 ) 
Ferric oxide (Fe 2 3 ) 
Ferrous oxide (FeO) . . 
Manganous oxide (MnO) 
Lime (CaO) 
Magnesia (MgO) 
Potassium-oxide (K 2 0) 
Sodium-oxide (Na 2 0) 
Titanium-oxide (Ti0 2 ) 
Carbonic anhydride (C0 2 ) 
Water and organic matter 



0-48 
2-81 
0-42 
2- 17 
0-25 
3-79 
1-44 
018 
2-56 
2-40 



Total 



99-72 



65 

(B.) The Andesites and Dacites. 

Distribution. 

The andesites and dacites throughout the whole suhdivision are rarely distinguishable mega- 
scopically from each other, and are closely related petrographicallv ; they have therefore, for 
purposes of convenience, been considered together. 

The effusives have but a minor development in the northern portion of the subdivision. Lavas 
and consolidated breccias form a small area, which includes the sharply conical peak (elevation, 2,898 ft.) 
immediately to the south-east of the main crest of Te Moehau .Mountain. This isolated patch lies at 
the greatest height which effusive rocks attain in the whole subdivision, and points to the removal by 
denudation of much volcanic material from the surface of the old rocks in the surrounding area. 

The main belt of the " First Period " volcanics is continuous from near the north-eastern corner 
of the Harataunga Survey District to the southern limits of the suhdivision. but the boundaries, as the 
accompanying maps will indicate, are extremely irregular. The northern prolongation of this belt 

n the eastern side of the mountain divide, between the old sedimentaries which form the higher 
portion of the range and the volcanics of the " Second Period " which form the hilly coastal belts. To 
the north-east of Cabbage Bay the rocks under consideration attain the crest of the main range, and 
from here, except for the interposition of the small rhvolite belt already described, continue uninter- 
ruptedly southward along the drainage-divide to the Tokatee Saddle, where it gives place to the rocks 
of the Tokatea Hill Series. Southward from the locality named the volcanics again form the crest of 
the main range, and continue to and beyond the southern limits of the subdivision. A stretch of seme 
two to three miles of the range, however, is dominated by the Castle Hock dyke, an intrusive in these 
volcanics (see page 92). 

Both on the eastward and westward sides of the mountain divide, from the Cabbage Bay section 
of this range southward to the limits of the subdivision, the rocks of the " Kirst Period " have con- 
siderable development. They form, with the exception of the sedimeutarv rocks already described, 
the whole of the main range, but seldom extend to the coast-line of the peninsula, as they are, over 
considerable stretches, flanked by the volcanic rocks of the " Second Period " (Beesoifs Island Series). 
On the actual western coast-line tin r within the Coromandel Harbour m the vicinity of Kevin 

Point and Pr se's Point, while on the eastern coast-line they are exposed in the rear of Matamata- 

harakeke Beach, and near the margin of W'hangapoua Harbour. 

Structure, <//"/ Conditions of Eruption. 

The andesites and dacites of the " First Period " overlie the folded Jurassic and Pre-.Jurassic 
sedimentaries, and were extruded upon a surface of very irregular relief, as proven by the great dis- 
parity in the elevations of neighbouring areas of the old rocks underlying the cxtrusives. 

These volcanics consist of tuffs, breccias, an I lava-How-, the pyroclastic rocks on the whole pre- 
dominating. The nature of these materials ami their disposition, so far as this is determinable, are such 
as would lead to the conclusion that they have been extruded from a number of vents. The actual 
locality of any of these vents or foci of eruption is not apparent, owing to the great alteration of the 
rocks and the extensive denudation that has taken place since this period of eruptive activity. It is 
probable that some of the earliest eruptions were submarine, but there are clear evidences of the ter- 
restrial conditions under which a great part of the volcanic accumulations was extruded. From the areal 
distribution of the volcanic rocks, and the prevailing north-and-south strike of the larger intrusive 
1> ts, it is probable that the vents or foci of eruption were disposed in a general meridional alignment. 
This would imply that fissuring of the sedimentary rocks, or zones of weakness, were induced 
parallel to the strike of the major folds, and that vents which were the centres of more or less intense 
volcanic activity existed at irregular intervals along these lines. There is apparently no definite order 
of succession among the different s -mi-basic members of this formation, it being difficult to identify a 
particular flow rock or breccia-bed even in two neighbouring localities. Bv far the greater portion 
5 — Coromandel. 



66 

of the main belt of the volcanic rocks occurring within the Harataunga Survey District is fragmental, 
more especially in the lower horizons, but flows and also intrusives are not uncommon. 

Within the Coromandel Survey District one of the best sections on the eastern side of the main 
divide is that taken from a point some 20 chains south of Trigonometrical Station UU, on the crest of 
the main range, across the Waikoromiko and Kopurukaitai Valleys. The rock here occupying the lowest 
position in the section, and overlying the Tokatea Hill Series, is a heavy flow of grey porphyritic horn- 
blende andesite ; this is overlain by a flow of dark basaltic-looking andesite, which forms the principal 
rock of the Four-in-Hand Mine, and is itself overlain by heavy beds of tuffs and breccias. The whole 
series dips in an easterly direction, and represents a thickness exceeding 2,000 ft. 

Within the Coromandel Valley mining operations have afforded some interesting information. 
The rocks of the Kapanga and Scotty's Mines, situated near the western base of Tokatea Hill, are fine- 
grained tuffs interstratified with solid flows of andesite and dacite. The Kapanga shaft (with a collar- 
elevation of 240 ft. above sea-level) has been sunk to a depth of 1,000 ft., and from the bottom of the 
shaft a borehole has been put down a further distance of 225 ft. The final 500 ft. to 600 ft. of this total 
distance of 1,225 ft. was sunk entirely through tuff beds, which dip at low angles to the west or south- 
west. At a depth of 940 ft. from the surface, or about 700 ft. below sea-level, a coal-seam, considerably 
silicified and pyritised, having the same disposition as the tuffs mentioned, was encountered. This band 
of coaly material, over 2 ft. in thickness, not only indicates a considerable period of quiescence between 
successive eruptions, but is cogent evidence of a considerable depression of this portion of the area 
subsequent to or contemporaneous with the eruptions which were productive of the upper 940 ft. of the 
accumulations. Several carbonaceous seams may be mentioned as occurring within and near the 
Triumph mining area, about a mile and a quarter further north than the Kapanga Mine. Since the 
bedded tuffs of the Kapanga Mine rise gradually towards the north — that is, in the direction of the 
Triumph Mine — it is quite possible that some connection exists between the carbonaceous deposits of 
the two areas, and therefore that these indicate one and the same old land-surface. 

Within the area of the Hauraki group of mines, north of Kevin Point, on the shore-line of Coro- 
mandel Harbour, the rocks are in great part highly altered flow andesites, but here, as at the Preece's 
Point Peninsula some 70 chains to the southward, fragmental rocks also exist. Andesitic tuffs con- 
stitute the main mass of the country rock of the Success Mine and other mines in its vicinity on 
the western flank of the main range south of Kaipawa Mountain Below i the Success Mine the 
road-cuttings, at an elevation of 590 ft. , expose the tuffs and breccias resting on the highly inclined 
sedimentaries of the Tokatea Hill Series. At one point a remnant of lacustrine beds is seen lying in a 
small depression on the ancient land-surface. The lacustrine deposits consist of fine argillitic conglome- 
rates or pebble-beds with thin mudstone partings, and a coal-seam of some 6 in. in thickness. 

In the lower portions of the Waiau River Valley, flows of dark basaltic-looking andesite directly 
overlie the sedimentary rocks, but at higher elevations in this valley andesitic breccias predominate. 
Some of these breccias have a peculiar conglomeratic appearance, as if a portion of the extrusive frag- 
mental material had been affected by fluviatile agencies prior to consolidation and envelopment by the 
products of later eruptions. 

In the area further south, an east-and-west sectional line drawn from the middle course of the 
Taurarahi Stream (Manaia Valley) on the western side of the divide, to the junction of the Waitaka- 
tanga and Mahakdrau Streams on the eastern side of the divide, lies wholly within these rocks. This 
line measures over five miles in length, and crosses the divide at an elevation of about 1,300 ft. The 
actual disposition of the rock on the western side of the divide is not apparent. From the point of 
contact of the volcanics with the Manaia Hill Series in the Taurarahi Creek, to the crest of the range, 
massive andesite, in all stages of alteration, occurs. On the eastern slopes of the range tuffs and brec- 
cias with minor flows of andesite form the volcanic pile, the whole series having a general dip at low 
angles to the eastward. The ancient foci of eruption here may, in position, correspond'- approximately 
with the highest points of the mountain divide. 

The general disposition of these " First Period " volcanics with reference to the older and younger 
rocks of the area is shown in the sectional maps accompanying this report. 



67 

Petrology. 

Megascopic C 'haracters. — In appearance the freshest specimens of the massive andesites 
and dacites are usually dark - coloured, dense, and finely porphyritic, showing small scattered 
glistening phenocrysts of plagioclase feldspar. Less frequently, owing to the greater abundance of 
phenocrysts, of which plagioclase is the most important, the rocks are lighter-coloured and assume 
various shades of grey. A greenish tinge, which is due to the presence of chlorite and other secondary 
minerals, is of general occurrence. The rocks occurring in certain relatively large areas are highly pro- 
pylitised, and in many of the mine-workings present the appearance of a whitish kaolin-like mass, in 
which little more than secondary pyrite can be readily identified. All stages of gradation exist between 
these light-coloured highly propylitised rocks and the dark-coloured comparatively fresh rocks. 

The andesitic tuff-;, breccias, and agglomerates arc well consolidated, particularly those of the lower 
horizons, which constitute the ejectamenta of the earlier eruptions. Owing to the greater perme- 
ability of these fragmentals they arc invariably altered to a considerable extent . In the case of the 
older accumulations the larger fragments arc no better preserved than the tine cementing material, 
and the original nature of the rock is difficult to determine. Certain of the later breccias, however, 
afford fragments of fairly fresh massive rocks, and these are always identical with those occurring as 
lava-flows or intrusive-. These volcanic fragmentals are normally of whitish, light-grey, or greenish- 
grey colour : the most abundant types appear to be breccias, consisting in the mam of angular fragments 
ranging from 2 in. to 4 in. in their largest dimensions. Within the propylitic areas the tuffs and brec- 
cias are altered to a light-coloured kaolin-like mass, frequently not to be distinguished from the pro- 
pylitic stage of the massive rocks. Tin' appearance and nature of the weathered products of these pyro- 
clastic rocks are in general the same as those of the massive andesites and dacites already described. 

The andesites and dacites are very prone to surface weathering, and arc very frequently covered 
to a considerable depth with the debris resulting from their decomposition and disintegration. This 
material is coloured various shades of red, brown, and yellow, due in great measure to hydratcd ferric 
oxides. The tendency of many of the 'massive How rocks and the solid inclusions in the breccias to 
weather spheroidal ly is an interesting phenomenon, and cores of hard fresh rock encased in concentric 
exfoliating layers are of frequent occurrence. As alreadv indicated, the different types of andesitic and 
dacitic rocks of the " First Period " are rarely distinguishable from each other megascopically, and 
this statement is more particularly true of the finer-textured varieties, which constitute by far the 
greater bulk of the volcanics. While microscopic examination admits of the s paration of these rocks 
into several types, according to the dominant ferro-magnesian constituent, the petrographical structure 
of the rocks in general and the nature of the several mineral constituents may be considered irre- 
spectively of the separate types. 

Structure of the Matrix. — Two distinct types of matrix or groundmass, as well as a third of some- 
what general character, are recognisable. The first two types are the hvalopilitic and the micropce- 
cilitic (pilotaxitic), as defined by Sollas. The latter is far more common that the former, which is 
characteristic of only a minor percentage of the " First Period " rocks. The third type is the micro- 
crystalline or finely granular groundmass, and is, next to the microprrcuitic. the one of most frequent 
occurrence. 

In respect to the hvalopilitic and pilotaxitic(?) matrices of the Hauraki andesites and dacites, 
Professor Sollas, who has examined a great number of the rocks, remarks": — 

" The nature of the matrix in the andesites and dacites offered a very difficult problem, and one of 
some importance, since in many cases the matrix contributes one-half to the bulk of the rocks. Rosen- 
busch clearly perceived the obvious existence of two types, which he distinguished as hvalopilitic and 
pilotaxitic. The first presents no difficulty : in it the mineral constituents of the rock, felspar laths, 
and the like, are immersed in a glassy base. The second is more obscure, and was defined by Rosen- 
busch as consisting entirely of a felt of microliths or minute crystals. I have never seen such a matrix 
in this class of rock. As a matter of fact, the second type of matrix differs from the first in this : that 
the glass of the hvalopilitic matrix is replaced by amosaic of 'crystalline grains, which, by reason partly 
of their irregular jagged outlines, partly of the similarity of their refraction index to that o^the felspar 
•0" — Coromandel. 



68 

microliths, are very difficult to diagnose, especially when, as frequently happens, they are very minute. 
When the structure is coarser, however, they may be plainly recognised as quartz, a conclusion long 
ago reached by Williams and Iddings, and one which I can completely confirm by the decisive observa- 
tions that when, as in the dacites, primary grains of obvious quartz are present, the mineral forming the 
pilotaxitic mosaic surrounding them can be traced into optical continuity with these grains. Thus the 
glass of the hyalopilitic matrix is represented in a number of definitely ascertained cases by the quartz 
of the pilotaxitic matrix. Williams and Iddings have given the name ' micropcecillitic ' to such a pilo- 
taxitic structure, and this term may in most cases be substituted for ' pilotaxitic ' wherever the latter 
occurs in my report. It does not follow, however, that the pilotaxitic structure is invariably an expres- 
sion of micropoecillitic quartz ; some other mineral might conceivably play the same part as quartz. 
A second species of felspar might do so, and though this may be regarded as improbable, yet its possi- 
bility must be borne in mind ; and since descriptions should, as far as possible, express facts, and not 
hypothes< s, I may here state that whenever I have used the word ' pilotaxitic ' in this report it must be 
taken simply to indicate that the glass of the hyalopilitic matrix is replaced by a crystalline substance 
forming mosaics. 

" It will be seen from this that the andesites are divided from the dacites by a very narrow line ; 
both contain quartz. Rosenbusch has proposed to distinguish the dacites by the presence of quartz 
as a phenocryst, but Zirkel points out that many rocks which, as proved by analysis, are true dacites do 
not possess such primary grains of quartz. No doubt the presence of primary grains of quartz is a sure 
indication that we are dealing with a dacite, but their absence does not prove the contrary, and thus 
there are numerous cases where the application of the name ' dacite ' or ' andesite ' must depend on 
the judgment of the observer. Chemical analysis can be the only court of ultimate appeal in such 
cases. * 

Throughout vol. ii of " Rocks of Cape Colville Peninsula," Professor Sollas substituted the term 
" micropoecillitic " for " pilotaxitic," which was used in vol. i. In the present bulletin the term " micro- 
poecillitic " has been used with the signification expressed in the above quotation. In order to 
avoid tedious repetition of these adjectival terms in the subsequent descriptions, (m.) placed after 
the word " andesite " or " dacite " will signify " rnicropoecilitic " ; (h.) will signify " hyalopilitic." 

The andesites and dacites having a micro-crystalline, finely crystalline, or finely granular matrix, 
show gradations towards their hypabyssal equivalents, the porphyrites. 

General Character of the Phenocrysts. — The plagioclase feldspars, the most abundant constituents 
porphyritically developed in all the andesites, generally range from andesine to labradorite. The 
more acid types, albite and oligoclase, and the more basic, anorthite, are, however, occasionally present, 
the specific gravities determined by Sollas having an extreme range from 259 to 2"78. It cannot be 
affirmed that the more acid or the more basic plagioclase characterizes any particular type of rock, 
and the possibility of the presence of the whole series — albite to anorthite — in a single specimen of an 
hypersthene andesite (from Preece's Point, Coromandel) is reported by Sollas.f The general habit, 
the zoning, the twinning, and the inclusions which characterize the plagioclase phenocrysts of^andesitic 
rocks are all exhibited in those occurring in the particular rocks under consideration. Orthoclase is of 
very rare occurrence in these effusives, although it is sometimes present in the porphyrites and diorites. 
Carbonates and sericite are the usual alteration-products of the feldspar, while pseudomorphs of chlorite 
are also very common. 

Hypersthene, using the term in its wider signification to include the lighter-coloured variety 
enstatite, is by far the most commonly occurring ferro-magnesian constituent of these andesites. It 
not only forms the characteristic mineral of a very common rock-type, but is an important subsidiary 
mineral in almost all the other groups. Under the microscope the crystals vary in ordinary light 
from colourless to reddish brown, those of the more pronounced colour exhibiting the deeper 
pleochroism. The most common alteration-products are a greenish fibrous serpentine, which is 
generally disposed along fractures or cleavage-cracks, and chlorite, which is formed under somewhat 

* " Rocks of Cape Colville Peninsula," vol. i, 1905, p. 118. f Loc. cit, vol. i, 1905, p. 134, 



69 

similar conditions. The usual replacement pseudomorphs are carbonates and chlorite, with occasion- 
ally quartz, epidote, and a greenish biotite. 

Augite rarely occurs as the dominant ferro-magnesian constituent, but, in association with an 
approximately equal amount of hypersthene, constitutes the pyroxene andesites of the classification 
adopted. The mineral, which is colourless or greenish grey with occasionally faint pleochroisni, 
takes the form of single crystals or of clusters of crystals, the latter often showing irregular inter- 
growths with hypersthene. The crystals, which often show rounded edges, are on the whole smaller 
than those of hypersthene. The alteration products are similar to those of the rhombic pyroxenes. 
Uralitisation has not been detected in the case of the augite of the effusive rocks, although occurring in 
their hypabyssal analogues. 

Hornblende is of much less frequent occurrence than either the rhombic or monoclinic pyroxenes 
in the volcanics of the " First Period," and, as might be expected, is more characteristic of the dacites 
than of the andesites. This mineral is not as stable as the pyroxenes, and is generally recognisable 
only by the outlines of its pseudomorphs. When fresh the hornblende is strongly pleochroic, varying 
in colour from yellowish-brown or sage-green to faint straw-yellow, and exhibiting dark reaction 
borders. The extinction angles range up to 20°. Pseudomorphic products consist of finely comminuted 
magnetite, minute pyroxene granules, chlorite, carbonates, quartz, hydrated ferric oxides, and 
leucoxene. 

Quartz, as a primary constituent determining the dacitic type of rock, is always very sparsely dis- 
tributed. It occurs either as medium-sized rounded grains, which arc often corroded by the matrix, 
or as small angidar grains in the interstitial material. Small bipyramidal crystals have also been 
observed. 

Other primary mineral constituents present are magnetite, ilnienite. zircon, and apatite. The 
original iron-ores, magnetite and llmenite, occur as fairly large crystals or small granules, and are often 
of considerable abundance. The presence of titanium-oxide (TiO a ) to the extent of 0*6 to 09 per cent, 
in the rocks is indicated by all the analyses. Tin' titaniferoua minerals give rise to the alteration- 
product leucoxene. Small zircons, together with needles .i\[i\ minute crystals of apatite, are sparingly 
distributed throughout some of the rocks. 

Olivine might be expected to occur, considering the preponderance of pyroxene-bearing andesites, 
but its presence has not yet been detected. 

Primary biotite is singularly absent from the volcanic rocks of this period, though occurring 
abundantly in some of the diorites and porphyrites of the Moehau area. 

Secondary products already mentioned are carbonates, sericite. chlorite (most common variety, 
pennine), fibrous serpentine, quartz, epidote. greenish biotite, magnetite., leucoxene, and hydrated 
ferric oxides. The biotite occurs only to a small extent, and generally in connection with complex 
pseudomorphs replacing ferro-magnesian minerals. Rutile and sphene are even more rare constituents 
of the same pseudomorphs. Pyrite is a common secondary mineral, especially in those volcanics which 
have been subjected to propylitisation. (See pa^e 75.) 

Types of the Volcanic Rocks of the " First Period." — The following types of volcanic rocks may 
be established : — 

(a.) Hypersthene andesites : Andesites, with hypersthene the dominant ferro-magnesian 
constituent. 

(b.) Augite andesites : Andesites, with augite the dominant ferro-magnesian constituent. 

{c.) Pyroxene andesites : Andesites, with pyroxenes (rhombic and monoclinic, in approxi- 
mately equal association) the dominant ferro-magnesian constituent- 

(</.) Hornblende andesites : Andesites, in which hornblende is the dominant ferro-magnesian 
constituent. 

(e.) Dacites : Rocks of andesitic type, in which quartz occurs as phenocrysts. 

Between the four first-named types there exists every gradation, and the position therefore of 
certain rocks in the classification adopted rests largely on the judgment of the observer. Thus, 
hypersthene andesite occurs in which hornblende, though a subordinate ferro-magnesian constituent, 



70 



is relatively abundant ; this has been termed hornblende hypersthene andesite ; similarly hypersthene 
hornblende andesite may be distinguished, and the line of demarcation between these two varieties 
must in certain cases be an arbitrary one. 

The dacites are, like the andesites, separable into several varieties according to the dominant ferro- 
magnesian constituents. These rocks, however, have in general such close mineralogical affinities 
with the andesites that they are often very doubtfully distinguishable from them. 

(a.) Hypersthene Andesites. — Hypersthene andesite, using the term to cover also the several 
varieties of this rock, is apparently the most widely spread type of the " First Period " semi-basic 
volcanics. It is. furthermore, the type of greatest economic importance, in that it constitutes the 
whole or the major portion of the country rock of many of the principal mining claims. 

A fairly typical specimen is that which occurs, both comparatively fresh and in all stages of 
alteration, in the Four-in-Hand Mine, Waikoromiko. When fresh this is a compact dark basalt-like 
rock, in which small phenocrysts of feldspar and ferro-magnesian minerals are recognisable megascopic- 
ally. Under the microscope the groundmass, which constitutes more than half the rock, is- micro- 
poecilitic with numerous rectangular feldspar laths, minute pyroxenes, and magnetite. Flow 
structure is fairly conspicuous. The phenocrystic plagioclase is of the usual andesitic character, 
the extinction angles indicating a range from andes'ne to labradorite ; hypersthene, as elongated prisms 
and aggregates, is, of course, the dominant ferro-magnesian mineral, and shows considerable alteration 
to chlorite and to a green serpentinous mineral. Aug te is present to a much lesser extent than 
the rhombic pyroxene. A few fairly large scattered grains of magnetite occur. 

As secondary minerals, pyrite, sericite, carbonates, quartz, and epidote are all present in greater 
or lesser amount, according to the stage of alteration of the rock. 

An analysis of a sample of this hypersthene andesite, taken from the Four-in-Hand low-level 
crosscut, is as follows : — 

. . 55-58 
.. 17-27 



Silica (Si0 2 ) 
Alumina (A1 2 3 ) 
Ferric oxide (Fe 2 3 ) 
Ferrous oxide (FeO) 
Manganous oxide (MnO) 
Lime (CaO) 
Magnesia (MgO) 
Potassium-oxide (K 2 0) 
Sodium-oxide (Na 2 0) 
Titanium-oxide (Ti0 2 ) 
Carbonic anhydride (CO,) 
Water and organic matter 

Total 



112 
741 
0-40 
7-30 
4-85 
0-46 
1-50 
0-67 
145 
2 05 

100 06 



This hypersthene andesite appears to extend' eastward from the headwaters of the Waikoromiko 
Creek, and forms the greater part of the spur between this stream and the Kopurukaitai. This is the 
spur upon which the Four-in-Hand Mine is situated. A similar rock, though considerably altered, 
appears in the Mangatu Creek, which, like the Waikoromiko and Kopurukaitai. is a tributary of the 
Harataunga, draining into Kennedy's Bay. 

A fairly fresh hypersthene andesite (m.) containing a little augite. forms Trigonometrical Sta- 
tion UU, on the crest of the main divide. Further northward in Austral Hill is seen an hypersthene 
andesite having what seems to be a remnant of glass in the matrix (hyalopilitic ?), also a few sparselv 
scattered hornblende phenocrysts. In Matamataharakeke Creek, about four miles to the north-east 
of Austral Hill, is found an altered rock somewhat akin to the andesite last described. 

Within the watershed draining into the Coromandel Harbour, hypersthene andesites are of very 
general occurrence. They have been described by Sollas and McKay, from the Britannia Mine, near 
the western base of Tokatea Hill ; from Preece's Point, near its north-western extremitv : and from 



71 



the Bunker's Hill Claim, at the quarry on the foreshore of Coromandel Harbour. That from Preece's 
Point is a typical hypersthene andesite, but is rather remarkable as containing possibly the whole 
range of plagioclases from albite to anorthite. That from Bunker's Hill Claim contains, as subsidiary 
ferro-magnesian minerals, both hornblende and augite. Certain other rocks collected were designated 
" pyroxene andesites," owing to alteration processes having rendered the original nature of the 
pyroxenes doubtful. Regarding one of these " pyroxene andesites " from the Kapanga Mine, at a 
depth of 1.200 ft. from the surface or 960 ft. below sea-level. Sollas remarks, " The outlines of some 
[of the pseudomorphs] suggest hypersthene " * It is therefore likely that the rock should appear 
with the hypersthene andesites of the present classification. Further south, in the main southerly 
headwater branch of the Waiau River, is found a hornblende hypersthene andesite having a remnant 
of glassy base ; this rock contains a rather unusual amount of secondary carbonates in mosaic-like 
patches. 

On the eastern side of the main divide hypersthene andesites (m.) are described by Sollas and 
McKay from Blackstone Creek, Opitonui Creek, and the Maiden Mine — all in the main Whangapoua 
Valley. Further south, in the watershed of the Mahakirau River, similar rocks were collected and 
determined by the writers, from Waitakatanga Creek. Rocky Creek, and Sparrow Creek ; they 
doubtless form a great part of the altered rock of the Mahakirau Valley. 

(6.) Augite Andesites. — Andesites of the " First Period.'" in which augite is the dominant ferro-mag- 
nesian constituent, are rare. Of the many microscopic sections made by the writers only two could 
be designated " augite andesite,'' while none have been reported by Sollas and McKay from the Coro- 
mandel subdivision. 

One of the two rocks referred by the writers to this type was taken from the cutting of the Coro- 
mandel-Cabbage Bay Road, at the head of Whaiwango (Big Paul's) Creek. Megascopically it is a dark 
finely textured rock, with a few small glistening feldspar phenocrysts. Under the microscope the 
groundmass is microptecilitic of the usual character, and constitutes about half the rock. The pheno- 
crysts are plagioclase of the labradorite type, augite in considerable abundance showing much lamellar 
twinning, and magnetite as scattered cubes and grains. 

The locus of the other specimen mentioned is a cutting in the vicinity of the Maiden Mine, Opito- 
nui, and the rock is an obscurely microp ecilitic augite andesite with a little hypersthene. As, how- 
ever, hypersthene andesites occur largely in the same vicinity, this augite andesite may be only a phase 



of the former more commonly occurring 
An analvsis of this augite andesite 

Silica (Si0 2 ) 
Alumina (Al.,0,) 
Ferric oxide (Fe 2 3 ) 
Ferrous oxide (FeO) . . 
Manganous oxide (MnO) 
Lime (CaO) 
Magnesia (MgO) 
Potassium-oxide (K 2 0) 
Sodium -oxide (Na 2 0; 
Titanium-oxide (Ti0 2 ) 
Carbonic anhydride (CO,) 
Water and organic matter 
• 
Total 



type. 

rom near the Maiden Mine is as under : — 



53-28 
17 54 
1-20 
7-92 
0-78 
7-70 
5-26 
0-26 
201 
3-61 
1-24 
"•08 



99-88 



(c.) Pyroxent Andesites. — The andesites. in which monoclinic and rhombic pyroxenes in approxi- 
mately equal proportion constitute the dominant ferro-magnesian minerals, are of common occurrence. 
Their general megascopic and microscopic characters differ in no respect from those of the type? 



* "Rocks of Cape Colville Peninsula," vol. i, 1905, p. 165. 



72 

already described. In none of the specimens from the various localities to be cited was a hyalopilitic 
groundmass observed, although in some sections the groundmass might be termed obscurely micro- 
pcecilitic — that is, only slightly differentiated from isotropic or glassy material. 

On the eastern side of the divide pyroxene andesite (m.) forms the solid spheroidal cores of the 
altered rock enclosing the " Silver Lode " in Tangiaro Creek, Port Charles. A similar rock, and also 
rocks with finely crystalline groundmasses, appear, further south, to form a large part of the volcanics 
incised by Waikawau Creek and its main confluent the Waikanae. 

Within the Kennedy's Bay watershed a dark basalt-like pyroxene andesite occurs in the valley 
of the left branch of the Kopurukaitai Creek, about 30 chains above the main fork, and also near the 
Four-in-Hand battery ; this rock probably represents only a slight differentiation of the upper part 
of the hypersthene andesite lava-flow, which forms the main mass of the spur between the Kopurukaitai 
and Waikoromiko Creeks. Within the valleys of the southern tributaries of the Harataunga, dark 
fine-textured pyroxene andesites (m.) occur near the heads of the Mataiterangi and Wairakau Creeks. 
The pyroxene andesites of the Mangatu Creek contain a little hornblende, while a specimen collected 
from the Omoho Creek, about 60 chains from the Harataunga junction, shows this mineral as small 
sharply outlined crystals, in sufficient quantity to warrant the rock being termed a hornblende pyroxene 
andesite. 

Within the Whangapoua Valley certain decomposed andesites (m.) obtained from the Waitekuri 
Stream may perhaps be grouped with this type, although the pyroxenes in these rocks are not abundant 
nor are they sufficiently well preserved to enable their specific character to be determined. Further 
south in the Mahakirau Valley the type is represented in the andesite of the middle course of Rocky 
Creek. 

On the western side of the divide certain rocks from the Britannia and Kapanga Xorth Mines 
(Coromandel) have been designated by Sollas* " pyroxene andesites," evidently on account of the 
pseudomorphic products obscuring the original character of the pyroxenes. 

South of Coromandel a fine-grained greenish-black rock with minute shimmering phenocrysts 
is seen in the road-cuttings a short distance west of the Opitonui Saddle. The pyroxenes are con- 
siderably altered, but apparently both the rhombic and the monoclinic types are equally abundant. 

Remnants of fine-grained dark andesite occur in the much-altered rock of the road-cuttings 
in the Waiau Valley within 1 i chains of the saddle ; this rock proves to be an obscurely rnicropoecilitic 
pyroxene andesite. The type is also represented in the inclusions of massive rock in the breccias of 
the Awakanae Creek and further south in the head of the Tupa Creek, a tributary of the Manaia River. 
Both these rocks have a rnicropoecilitic matrix, and that from the Tupa shows among the phenocrysts 
a few small crystals of hornblende. 

(d.) Hornblende Andesites. — The effusive hornblende andesites of the " First Period "<are confined 
to a few localities, and have close affinities with the hornblende dacites, which are of rather more general 
occurrence. 

The best-defined belt of hornblende andesite is that extending from the Harataunga Stream up 
the valley of the Waikoromiko Creek. The rock is in general light grey and rather coarsely porphyritic, 
but shades into a darker finer-textured variety. Under the microscope the light-grey rock is seen 
to have a finely crystalline groundmass, consisting in the main of feldspar with a few minute hornblendes. 
Secondary quartz is present and occasionally, possibly, a little primary quartz. The darker fine-grained 
rock shows a micropcecilitic matrix, and occasionally exhibits flow structure. The phenocrysts of plagio- 
clase are in general considerably altered to carbonates and sericite, or are replaced by pseudomorphs 
of chlorite. Greenish to dark-brown hornblende, with resorption borders, is conspicuous as prismatic 
individuals and aggregates, but is often considerably altered. Hypersthene and augite occur to a 
very minor extent, also magnetite, ilrnenite, and their secondary products. Pyrite in small cubes and 
irregular grains is disseminated sparsely throughout the rock. Some of these rocks might well be 
designated " porphyrite " or " andesite porphyry," did not the field evidence suggest that they 
constitute lava-flows rather than intrusive masses. 



* Sollas and .McKay: " Rocks of Cape Colville Peninsula," vol. ii, 1905, pp. 141, 144. 



73 

On the same (eastern) side of the main divide hornblende andesite is found in the headwaters of 
the Waitakatanga Valley, forming a great part of the included fragments of the altered pyroclastic 
rocks into which has been intruded the Castle Rock dyke. 

On the western side of the divide the dark fine-grained rock overhang the old sedimentaries at 
Pa Hill, Tiki, is a hypersthene hornblende andesite (m.). The same rock appears to have considerable 
development among the altered volcanics of the low grounds of the Tiki and Waiau Valleys. 

Among the many altered andesites of the Coromandel mining centre it is highly probable that 
some had hornblende dominant, but identifiable rocks of this type among those classed as " First 
Period " volcanics have not been detected in the area. 

An analvsis of a typical hornblende andesite from the Waikoromiko ( 'reek is as under : — 

Silica (SiO,) . . . . . . . . . . . . 57-25 

Alumina (A1,0 3 ) .. .. .. .. .. .. .. 16-39 

Ferric oxide (Fe,0 3 ) . . 0-40 

Ferrous oxide (FeO) .. .. .. .. .. 7 35 

Manganous oxide (MnO) . . . . . . . . 0*36 

Lime (CaO) . . . . . . . . . • . . . . 4-50 

Magnesia (MgO) . . . . . . . . . . . . 3-55 

Potassium-oxide (K 2 0) . . . . . . . . . . 1 -97 

Sodium-oxide (Na 2 0) . . . . . . . . . . 2-37 

Titanium-oxide (Ti0 2 ) . . . . . . 0-92 

Carbonic anhydride (CO a ) •• •• .. .. L-38 

Water and organic matter . . . . . . . . . . 3-26 



Total .. .. .. .. .. 99-69 

(e.) Dacites. — The dacites are, as already indicated, often separable from the andesites only with 
difficulty. Almost all of the volcanics of the " First Period " from the Coromandel subdivision, which 
were classed as dacites by Professor Sollas. and also those which have been determined as dacites by 
the writers of this bulletin, show considerable alteration. As dacites in a comparatively fresh 
state seldom or never occur, the primary nature of much of the quartz-content in the*a',tered rocks 
may be open to question. In general appearance and in structure the rocks differ in no respect 
from the normal andesites of similar states of alteration, except in the presence of recognisable free 
quartz. 

Within the watershed draining into Coromandel Harbour, certain rocks from the following mines 
have been pronounced dacitic by Professor Sollas : — 

Scotty's Mine — 

(a.) From underground workings : Light-grey decomposed pyritised rock ; altered dacit* 

with hornblende. 
(b.) From a depth of 250 ft. in mine : Bluish-grey felstone-like rock ; altered dacite. 

Britannia Mine — 

(a.) From workings : Light-grey (Inecciated) fine-grained, pyritised rock ; altered dacite 

(or andesite). 
(b.) Bluish-grey felstone-looking rock with obvious feldspar crystals ; altered dacite with 

hornblende, 
(c.) Greenish brecciated pyritised rock ; dacite or andesite. 

Success Mine — 

(a.) Upper level : Dark greenish-grey felstone-like rock ; dacite. 

(b.) Low level : Greenish-grey compact pyritised rock ; a much-altered hornblende dacite 
or andesite. 



74 



Kathleen Mine — 

(a.) 150 ft. to 200 ft. from surface : Greenish-grey decomposed porphyritic rock ; altered 

dacite. 
(b.) 150 ft. to 200 ft. from surface : An obviously decomposed rock ; altered hornblende 

dacite or dacite porphyrite. 

Hauraki Mine — 

From an unascertained locality in the mine-workings : Grey to black basaltic-looking rock, 
with large crystals of feldspar scattered porphyritically ; altered hornblende dacite or 
dacite porphyrite. 

A dark-greenish-coloured rock was collected by the writers from Whangarahi Creek (not far from 
the Britannia Mine, where the occurrence of dacites has been mentioned). Under the microscope this 
rock is seen to have a micropcecilitic groundmass. The plagioclase phenocrysts are of the usual ande- 
sitic character, but are in general considerably altered to calcite and sericite. Quartz occurs both as 
rounded grains (which may be primary) and mosaics (probably secondary). The pyroxenes are repre- 
sented only by pseudomorphs: The rock can only be termed an altered dacite or andesite, but, as no 
even moderately fresh sample was procurable, this doubtful rock was submitted for chemical analysis. 
The appended result shows a silica-percentage much too low for a dacite, and, even having regard to 
the considerable alteration evidenced by the quantity of carbonates present, the rock should more 
consistently be classed with the andesites. 



Silica (SiO 2 ) 






. 


. 48-90 


Alumina (A1 2 3 ) 








17-67 


Ferric oxide (Fe 2 3 ) 








1-20 


Ferrous oxide (FeO) . . 








7 06 


Manganous oxide (MnO) 








019 


Lime (CaO) 






. 


. 1100 


Magnesia (MgO) 








3-91 


Potassium- oxide (K 2 0) 








0-34 


Sodium-oxide (Na 2 0) 






. . 


1-89 


Titanium-oxide (Ti0 2 ) 








0-98 


Carbonic anhydride (C0 2 ) 








4-87 


Water and organic matter 








2-28 



Total .. .. .. .. .. .. 100-29 

Dacites have been identified from localities further south than these mentioned, but all are in 
a similarly altered condition. At the head of the main left branch of the Tiki Creek a hornblende dacite 
occurs, and in Bremner's tunnel, at the head of the Matawai Creek, the altered porphyritic rock proves 
to be a much-altered dacite or dacite porphyrite. 

On the eastern side of the main divide dacitic rocks occur in the Whareroa and Omoho Creeks, 
and much further south a hornblende dacite was identified from Batterv Creek, Mahakirau Valley. 



Propylitisation of the Volcanic Rocks. 

A very general alteration of the andesites and dacites is a characteristic feature of the vein- 
bearing areas of the subdivision. This alteration is best described as " propylitisation," the term 
being used to indicate the changes superinduced in andesites and similar rocks by solfataric action, 
which result in the formation of "propylite" as defined by Rosenbusch. 

The highly propylitised rocks, or propylites, have a white, greyish-white, or bluish-white colour, 
and a rather granular or earthy appearance. Opaque white pseudomorphs of feldspar and traces of 
ferro-magnesian minerals are sometimes observable, the former giving to the rock a rather spotted 



PLATE XX. 




Michoi'cecilitic Hypehsthene Andesite. Tertiart Volcanic Rocks oi Firsq Period, Preece's 

Point. ( 'orom indel. 

Magnification, 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Hull. S<>. .;.] 



face p. ?.',. 



plate xxi. 




M 1 1 i ; < >i'< i < iii 1 1 < Htpbrsthene Hornblende Andesite, Tertiart Volcank Rocks of First Period, 

Pa Hill, Tiki. 

M. unification. .'i:i diameters. Work <>t' Mr. Alexander McKay. F.G.S. 



Geo. Bull Xo. I] 



To tare [,. ?£. 



PLATE XXII. 




Proptlitised Andesite, Tertiary Volcann Rocks of Firsi Period, Haurakj Mine, Coromandel. 
Magnification, 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Dull. No. f] 



[Jo face p. 7j. 



75 

appearance. Pyrite is fairly abundant, and as a rule the further the propylitisation has progressed 
the greater is the amount of this mineral present. 

Under the microscope the feldspars are seen to be replaced by calcite, sericite, and quartz, and are 
sometimes impregnated with chlorite. The ferro-magnesian silicates are altogether dispersed, or their 
outlines are preserved by alteration products — chlorite, sericite, carbonates, quartz, and very rarely 
epidote. Pyrite is often present with the pseudomorphs after ferro-magnesian minerals, in addition 
to occurring as cubes and irregular grains throughout the rock generally. 

It seems likely that both silica and carbon-dioxide were- introduced by the agencies of thermal 
metamorphism during the periods of vein-formation, and it is quite certain that the ascendng waters 
or gises were sulphur-bearing. The amount of pyrite (the bisulphide of iron) present in the propylitic 
areas is relativelv very great, whereas the mineral is altogether absent from the unaltered rocks. The 
frequent occurrence of pyrite within the pseudomorphs after ferro-magnesian silicates, suggests that 
the pyrite was formed by the action of the sulphur-bearing waters on the iron ol the original 
minerals. Plate XXII (page 74) is fairly representative of the propylitised andesites and dacites 
under the microscope, and shows pyrite occurring within the area formerly occupied by the 
ferro-magnesian mineral. 

. According to Rosenbusch, " The characteristic feature of the propylitic. fades consists in the loss of 
the glassy habit of the feldspars ; in the ehloritic alteration of the hornblende, biotite, and pyroxene 
(often with an intermediate stage of uralite), witli simultaneous development of epidote ; further, 
in alteration of the normal groundmass into holocrystalline granular aggregates of feldspar, quartz, 
chlorite, epidote(?), and calcite, and in a considerable development of sulphides (usually pyrite)."* 

Inasmuch as the formation of epidote is not characteristic of the thermal metamorphism of the 
Coromandel andesites, the term " propylitic " is in this bulletin employed in a rather more general 
sense than that postulated by Rosenbusch. 



12.) TERTIARY VOLCANIC ROCKS OF THE "SECOND PERIOD" (BEE80N'9 ISLAND SKKTES). 

Genkrai, Statkmknt. 

The Tertiary volcanic rocks of the " Second Period " consist entirely of andeaitic and dacitic 
tuffs, breccias, agglomerates, and lavas. With these effusive rocks are associated numerous dykes 
of andesite and porphyrite, which m places, however, cannot be distinguished from the lava-Hows. 
Where the intrusive nature of these rocks 'is apparent they have been especially mapped, and are con- 
sidered in a later portion of this chapter. The effusive rocks form essentially coastal belts on both 
sides of the peninsula. Some of the belts, are of considerable extent transverse to the trend of the 
peninsula, and in places exceed 1,000 ft. in elevation, but never attain the crest of the mountain 
divide. 

In general, the fragmental rocks of the Beeson's Island Series are less well consolidated, and the 
lavas less decomposed and also less crystalline than those of the " First Period." 

A Miocene age has been assigned to the eruptive rocks under review, for reasons which will be here- 
after stated. The term " Bee&on's Island Series,'" as applying to these rocks, is well established, and 
is used as an alternative to " Tertiary volcanic rocks of the ' Second Period ' " in the present bulletin. 
Beeson's Island, where these rocks have their typical development, lies on the northern side of the 
entrance to Coromandel Harbour. 

It should be here remarked that where these rocks rlank and overlie those of the " First Period," 
the actual contact of the two series is frequently by no means apparent. On account of a general simi- 
larity in original composition of the earlier and later andesites, the question of determining a boundary 
often baffles solution, even when field-work is supplemented by microscopic study. The tracing of 
a connection between a doubtful phase and some characteristic phase in the rock-mass has, however, 
frequently allowed of a boundary being placed fairly approximately. 



* " Element d. a lehre," Stuttgart, 1898, V . 302. 



76 

Age and Correlation. 

The volcanic rocks of the " Second Period " or Beeson's Island Series were, in 1883, referred 
to the Miocene period by Cox, who remarked that the breccia-beds at Beeson's Island and certain 
other localities " are the same as those .... occurring at the Manukau Heads." In 
respect to the latter locality, which lies some fifty-five miles to the eastward of the Cape Colville 
Peninsula, Cox remarks that " the heavy angular volcanic breccias, which are regularly stratified, lie 
quite conformably on certain glauconitic sandstones, which pass down into the Waitemata marls as 
developed at Manukau Harbour." The Waitemata beds have been, on palseontological evidence, 
assigned to the Lower Miocene period, and include interstratified persistent beds of volcanic (andesitic) 
grits, which have been the subject of several geological notices and reports.* These andesitic grits 
occurring in definitely ascertained Miocene strata are sure proof of considerable eruptive activitv in 
Miocene times. It is therefore reasonable to infer, even apart from any lithological resemblances of 
the pyroclastic material at Beeson's Island and Manukau Heads, that the manifestations of vulcanism 
were not confined to the Waitemata- Manukau area, but must be held to account for part of the 
Tertiary andesitic complex of the Hauraki Peninsula. 

No proofs of the actual age of the Beeson's Island Series were observed within the Coromandel 
subdivision, but their unconformable superposition on the volcanics of the " First Period " is apparent. 
On the eastern side of the divide the dark glassy lavas and the heavy breccia-beds are found within the 
Kopurukaitai Valley overlying the highly propylitic andesites of the " First Period," and the abrupt 
termination of detrital gold in the stream-beds immediately the younger rocks are reached is very 
noticeable. On the western side of the divide; ft section taken from the coast-line near Torehine to the 
crest of the main divide near Austral Hill is suggestive of the removal by denudation of a con- 
siderable mass of the older volcanics before the younger accumulations were extruded, and therefore 
indicates unconformity between the two series. McKay, who has previously noted this, writes as 
follows : " At Cabbage Bay this unconformity [of the Beeson's Island Series] to the rocks of the Ka- 
panga (older) group is most marked. The rocks of the latter group had been removed from the middle 
and lower valley of the Umangawha and the slates laid bare before the commencement of the igneous 
outbursts, as a result of which the Beeson's Island rocks were deposited." t 

Park deduces the age of the " Second Period " volcanics from leaf-impressions obtained from the 
shales with thin coaly partings, which at certain places in the Hauraki Division occur at the base of 
the series. The localities Paparoa and Cabbage Bay (within the subdivision), where prospecting for 
coal was some years ago prosecuted, are mentioned among others. Concerning the various widely 
separated occurrences, this geologist remarks, "At all places they [the shales] contain numerous leaf- 
impressions and fragments of carbonised wood. The most characteristic plant-impressions are those 
of Dacrydinium cupressinum, Dacrydium sp.(?), and Podocarpium, which indicate a Miocene age for 
the volcanic rocks, with which they are associated." % 

In this bulletin, from consideration of the facts cited above, a Miocene age has been ascribed to the 
volcanics of the " Second Period " (Beeson's Island Series). 

Distribution. 

As already indicated, the effusive rocks of the " Second Period " or Beeson's Island Series con- 
stitute coastal belts on both sides of the peninsula. 

On the eastern coast-line a small area of breccias and agglomerates forms the conspicuous north- 
eastern headland near Sugar Loaf Rocks, this being the most northerly occurrence of these volcanics. 
Further to the southward rocks of this group, consisting mainly of coarse breccias, form comparatively 



* Hochstetter, F. von : " Reise der ' Novara ' : Geology," i, p. 34. Hutton, F. W. : Trans., vol. xvii, 1884, p. 307. 
Cox, S. H. : Reps. X.Z.G.S., vol. xiii. 1881, pp. 17, 25 ; vol. xiv. 1882. p. 27. Hector. J. : Reps. N.Z.G.S., vol. xiii. 
1879-80. McKay. A. : Reps. X.Z.G.S., vol. xvi, 1883-84. p. 102. Park, J. : Reps. X.Z.G.S., 1885, vol. xvii, p. 158. 
Mnlgan, E. K. : Trans., vol. xxxiv, 1901, p. 414. Fox, C. E. : Trans., vol. xxxiv, 1901. p. 452. 

f C.-9, 1897, p. 63. 

| Park, J. : " Geology and Veins of the Hauraki Goldfields," 1897, p. 36. 



77 

extensive coastal belts of hilly country. These have extension from Stony Bay to Waikawau Creek, 
from south-east of Matamataharakeke Beach to the north-eastern shores of Kennedy's Bay, and from 
the southern shores of Kennedy's Bay to Whangapoua Harbour. 

Much the largest area of these volcanics is that covering a great part of the Kuaotunu Peninsula 
and the hilly country lying to the north and west of the large alluvial flats of the Mercury Bay settle- 
ment. The western boundary of this area is a sinuous line extending southward from the shores of 
Whangapoua Harbour, near the mouth of Opitonui Creek, to a point near the junction of the Wai- 
takatanga and Mahakirau Streams. From this stream-junction the boundary continues in a southerly 
and then an easterly direction to the southern limits of the district. 

On the western side of the peninsula these rocks are not found further north than Cabbage Bay. 
They form the greater part of the range lying between the Umangawha Stream, Cabbage Bay, and the 
western coast-line, and, as a gradually narrowing belt, extend southward to the headwaters of Paparoa 
Creek. At a point on the coast-line some half a mile to the north of Paparoa Creek another coastal 
belt commences, overlying at Paparoa the rocks of the Manaia Hill Series. This narrow belt, excepting 
that it is concealed in two or three places by Recent fluviatile deposits, is continuous in a south- 
easterly direction to Kikowhakarere ; from here it extends in a south and south-westerly direction, 
forming Dacre Hills and finally the Ruffin Peninsula on the north side of Coromandel Harbour. 
Separated from this peninsula by a narrow tidal passage is Beeson's Island, the typical locality of the 
rocks of this series. On the mainland to the south of Beeson's Island the hilly country lying between 
the southern shore-line of Coromandel Harbour and Manaia Harbour, and deeply indented by Te Kouma 
HarbouT, consists entirely of fragments] rocks of the Beeson's Island Series : s<> also does the greater 
portion of the area lying between the southern shore-line of Manaia Harbour and the southern 
boundarv of the subdivision. Numerous small islands lying off the stretch of coast-line between 
Cabbage Bav and Manaia belong to this rock-formation. 



Structure, and Conditioss ok Kkuption. 

The extrusives of the " Second Period " consist in the main of irregularly stratified pyroclastic 
rocks, with which are associated at greater or lesser intervals intercalated lava-flows. Less fre- 
quently, however, the massive rocks are found forming almost exclusively relatively large areas. The 
pyroclastic rocks consist of fine clayey tuffs, sandy tuffs, sandy tuffs interspersed with lapilli, fine 
and coarse breccias, agglomerates, and all gradations between these more or less definite types. 
Certain natural sections afforded by the cliffs of the coast line show bedding-planes with some degree 
of regularity, other exposures show considerable thickness of pyroclastic material without any percep- 
tible arrangement. 

The earliest eruptions of this period were probably submarine, but there are abundant evidences, 
as will be cited later, of the sub icrial conditions under which a great part of the volcanic materials was 
extruded. The predominant paroxysmal character of these eruptions along both coast-lines of the 
peninsula would appear to be explainable on the assumption that sea-water had frequent and ready 
access to the vents. The fact is particularly noticeable that the massive rocks of this scries have their 
greatest development in those portions of the larger areas which are furthest removed from the sea- 
coast. Lavas are, for instance, much more abundant than fragmental rocks in that portion of the 
Kuaotunu Peninsula Range which approaches nearest to the main Cape Colville Range. 

On the western side of the peninsula the rocks forming the hilly coastal belts, which are brokenly 
continuous from Cabbage Bay to the southern boundary* of the subdivision, consist in the main of frag- 
mental material. The disposition of the irregularly stratified beds suggests that the principal foci 
of eruption lay to the west of the present coast-line. In this connection the existence of the chains of 
islands of similar formation lying off the coast-line is significant. In the extreme south-west corner of 
the subdivision, however, the persistent dip of the beds seaward from the sharp peak Pukewhakatara- 
tara (1,293 ft.), and the frequent occurrence here of very heavy lava-blocks, indicate the locus of a 
major explosive centre in the vicinity of this peak. The heavy agglomerates and the steeply inclined 



78 

columnar lava-streams of the outward extremity of Ruflin Peninsula also suggest that this is probably 
the locality of one of the minor vents. 

One of the most interesting and instructive sections on the western side of the peninsula is that 
exposed near the south headland of Cabbage Bay.* The rocks here are agglomerates, coarse and fine 
breccias, and sandy and clayey tuffs. Two or three old land-surfaces, on which grew a luxuriant vegeta- 
tion, are traceable within these bedded fragmentals. On one of these old surfaces roots and stumps of 
trees, the latter ranging up to 2 ft. in diameter, are found in their natural positions, the roots in the 
soil and trunks broken off a short distance above the ground-level. Heavy showers of ejectamenta, 
the products of eruption from an adjacent subaerial volcano, devastated and overwhelmed this 
ancient forested land, and have formed the coarse and finer grained breccias which surround and overlie 
the remnants of this forest. All of this vegetable material has been completely carbonised or silicified ; 
and considerable quantities of fossil wood may be seen strewn along the adjacent sea-beaches. 

At the head of the middle branch of the Paparoa Creek prospecting operations have revealed the 
presence of two thin erratically disposed seams of coal, enclosed in greasy slickensided shales, which 
evidently mark the base of the volcanic series. The greatest thickness of coal discovered was about 
4 in. 

On the coast-line north of Paparoa Creek heavy flows of dark-grey porphyritic andesite occur, but, 
between the creek named and Koputauaki, pyroclastic rocks consisting of both coarse and fine materials 
predominate, and enclose occasional fragments of silicified wood. These beds dip in general to the 
north-east — that is, in a direction away from the present sea-border. 

Flows of glassy andesite, tuffs and breccias, and dyke rocks, characterize the area lying between 
Kikowhakarere and Long Bay, and extending inland 30 to 80 chains. Similar rocks occur also in the 
continuation of this area as the narrow hilly peninsula which terminates at the Little Passage. 

Beefeon's Island and the coastal area extending from the south side of the Coromandel Harbour to 
the southern limits of the subdivision show a marked similarity in structure. The accumulations con- 
sist almost entirely of pyroclastic rocks, showing in many places a rude stratification. In addition to 
the usual phases of tuffs, breccias, and agglomerates, agglomeratic accumulations were observed, consist- 
ing entirely of black angular lava-blocks varying from larger to smaller dimensions without any fine 
cementing-material. These blocks are held together by their " slaggy " exterior surfaces, which there- 
fore were evidently plastic at the time when the ejectamenta reached their present position. Lava 
flows and dykes are rare occurrences in this particular area. 

Maclaren has, on the disposition of the pyroclastics, assumed the existence of a crater between the 
north headland of Te Kouma Harbour and Rangipukea Island, near the main entrance of Coromandel 
Harbour.f This hypothesis is further supported by the soundings as shown on the chart of this 
locality. 

On the small peninsula lying between the Manaia and Te Kouma Harbours dome-shaped hillocks 
are rather conspicuous features (Plate XXIII). The flanks of these hillocks show in places vertical 
rock-faces, well exhibiting the structure of the mass. Sandy light-coloured tuffs, which weather easily, 
form beds capped by bands of dark-coloured heavy agglomerates. The latter, owing to the resistance 
offered to weathering agencies, form a capping which overhangs somewhat the lower vertical walls of 
tufaceous material. 

On the north-eastern coast-line the small area forming the Sugar Loaf Headland shows all the 
pyroclastic rocks typical of the series, with brecciated lava-flows forming resistant buttresses. This 
is evidently a northerly remnant of the larger area, which has its present northerly termination on 
the south shore of Stony Bay. A very small patch of breccias is still preserved on the northern 
headland of the bay named. 

Between Stony Bay and Port Charles the rocks consist in the main of coarse and fine breccias, with 
here and there intercalated flows of dark andesite. Nests and irregular veinlets of calcite are not un- 
common in the finer fragmental material. 

The Port Charles Peninsula, together with the area northward of a line drawn due east from the 
junction of Tangiaro and Eel Creeks, to the outer coast-line is of interest, as the localities or near vici- 

* This section has been described by McKay— C. -9, 1897, p. 60. f c ~9> 1900, p. 10. 



PLATE XX 11 




Hillocks ok Stratified in lnd Agglomerates (Beeson's Island 
Series), between Te Kouma and Manaia Harbours. 




Stratified Tuffs and Agglomerai :s (Beeson's [si ind Series), forming 
Hills between Te Kouma and .\f anaia Harbours. 



Geo. Bull. No. f] 



[To face p. 78. 



PLATE XXIV 




l i+W 






Te Kouma Hah bo cm. 




Trigonometrical Station RR, Kennedy's Bay. (Peak consists of 
Andesitic Breccias.) 



Geo. Bull. So. If.] 



[To face p. 79. 



79 

nities of several centres of eruption appear to be suggested by the character and disposition of the accu- 
mulations. One of these craters probably existed to the north of Carey's Bay, another in the 
vicinity of the " Hanging Rock " to the south-east of the inner reach of Port Charles Inlet, while a 
minor one has been exposed by marine erosion on the outer coast-line some 85 chains south-east of the 
main northern headland. Almost all the volcanic products in these areas are pyroclastic, and include 
fragments of carbonised and silicified wood ; a massive columnar andesite, however, forms the pro- 
minent buttress of the northern headland. 

The continuation of this hilly coastal belt from Port Charles to Matamataharakeke Beach shows 
in the main similar pyroclastic material, with lava-streams and dyke rocks, the beds in general having a 
dip seaward. Silicified wood is not uncommon in the breccias, often as tree-trunks a foot or more in 
diameter. Further southward the coastal belt extending from Haupapa Point to Kennedy's Bay 
consists of rocks characteristic of the series. The pyroclastics greatly predominate, and the beds have 
a prevailing dip to the eastward. The northern coast-line of Kennedy's Bay exhibits breccias overlying 
a massive grey lava-stream. These breccias weather* in a variety of fantastic shapes, due largely to 
their fissured and cavernous nature. The more secluded of the caves they contain have been used as 
places of sepulture by the Maoris. 

The Kennedy's Bay - Whangapoua belt is not less characteristic of the rocks of the series than 
those already described. The boundary-line between these andesites of the Beeson's Island type and 
the andesites of the " First Period " is apparent in certain of the eastern branches of Kopurukaitai 
Stream. The comparatively fresh, dark, basalt-like lava-streams of the later period are in places found 
overlying the l'ght-coloured highly propylitic rocks of the older group. The resistance which the 
breccias and agglomerates of the " Second Period " frequently offer to weathering agencies is well 
exemplified in the existence of the bold peak which constitutes Trigonometrical Station RR (1,024 ft.) 
near Kennedy's Bay (Plate XX I V). The sharp outlines of this peak suggest the existence here of a 
dyke rock rather than the pyroclastic material of which it is actually composed. 

The Kuaotunu Peninsula and the continuation of this area south-westward to the Mahakirau 
Valley consist in greater part of fragmental and massive rocks, which are in the main typical of the 
Beeson's Island Series, and have, therefore, all been referred to the " Second Period." The 
rocks on the lower hilly volcanic country of the northern side of the Kuaotunu Peninsula are in 
general very much decomposed. Eastward from the alluvial fiats of the Opitonui Stream the weathered 
products are moderately characteristic of the series under description ; but an examination of the 
section afforded by the upper course of the Mapauriki Creek establishes the identity of the breccias 
existing here with those of typical areas of " Second Period " rocks. 

The section afforded by the Coromandel-Kuaotunu Road, passing north-eastward from the crossing 
of Mapauriki Creek to the coast-line at Materangi Bluff and from here eastward for about a mile, is 
instructive ; fine-grained andesitic and dacitic tuffs, breccias, and lava-flows, dipping in general to the 
south-eastward, alternate rapidly with one another, and present the general colorations and characters 
typical of rocks of this series. About half a mile south of this coast-line is the conspicuous sharp peak 
of Te Tutu (636 ft.), the most undoubted old volcanic crater yet located on the Hauraki Peninsula. 
A slip on the south-east side of the hill has exposed the old pipe or crateral vent, filled with agglomerate 
composed mainly of blocks of black glassy andesite. The walls of this pipe consist of consolidated 
fine tufaceous rock of lighter colour than the agglomerate neck. 

The outer end of the peninsula consists in the main of pyroclastic rocks, with intercalated flows of 
porphyritic andesite or dacite. The pyroclastics are in no way distinguishable from those at Manaia 
or Beeson's Island. Even the peculiar dome-shaped hillocks described as occurring at Manaia are 
paralleled in the area between Stewart Creek and Matapaua Bay. In the western portion of the Kuao- 
tunu area massive rocks form most of the higher country drained by the Opitonui, Owera, Taputapu, 
and Wade Creeks. Near the contact between the Beeson's Island Series and the volcanics of the 
" First Period," breccias and fine stratified tuffs occur. With these fine stratified sandy tuffs in Hooker 
Creek, and in the main left-hand branch of the Waitakatanga Creek, are associated coaly shales and very 
small seams of impure coal. The boundary-line between the two volcanic series here and north to 
Whangapoua Harbour is, as might be expected, a very intricate one, and can be mapped only approxi- 
mated 



80 

Petrology. 

Megascopic Characters. — The Tertiary volcanics of the " Second Period," as stated before, consist 
of tuffs, breccias, agglomerates, and lavas, and with these are associated intrusives not always dis- 
tinguishable from the lava-flows. The pyroclastics are much more abundant than the lavas. The 
tuffs and breccias in general resemble those of the " First Period," but are on the whole less well 
consolidated. 

Included fragments of massive rocks in the breccias and agglomerates are often comparatively 
fresh, whereas in the fragmentals of the " First Period " they are often in as poor a state of preservation 
as the softer matrix. The tuffs are generally light-coloured, and vary in texture from a fine clayev 
to a gritty, sandy mass. Such fragmental beds of fairly uniform character are well exhibited in the 
vicinity of Manaia Harbour and Kirita Bay. The breccias and agglomerates are in colour light-grev, 
purplish to dark grey, or almost black, the finer matrix generally showing the lighter colours. The 
included fragments are sometimes sparsely distributed throughout a tufaceous. rapidly weathering 
matrix, or again constitute by far the greater bulk of th.e rock, while occasionally (see page 78) heavy 
lava-blocks and rubbly angular fragments without matrix constitute the whole rock-mass. A rather 
less common type of these pyroclastics is that encountered on the coast-line of the Port Charles Penin- 
sula and at the extremity of Kuaotunu Peninsula. The white ashy matrix of certain breccias in these 
localities is speckled with fairly large perfect or fractured idiomorphic crystals of hornblende. 
It would appear certain that these crystals must have been contained in a fluid matrix before expulsion 
from the crater. These peculiar fragmental rocks recall the " crystal tuffs " of certain writers. 

The massive rocks vary in colour from light grey to black. On the whole the groundmass has a 
more lithoidal. glassy appearance, and the hornblende or hypersthene phenocrysts are perhaps more 
conspicuous than in the great majority of the rocks of the " First Period." 

The lighter-coloured massive rocks and included fragments of the pyroclastics present, on 
weathering, surfaces which are rough and prickly to the touch. This fact led to the rocks of the Beeson's 
Island Series being denominated trachytes by the early writers on the district, prior to the general 
introduction of petrographical methods for rock-determination. The surface debris representing 
the disintegrated and completely weathered rocks, even more so than in the case of the older volcanics, 
is characterized by variegated colorations of red, brown, and yellow, due largely to hydrated ferric- 
oxides. Many of the areas of the " Second Period " rocks, as, for example, the outer part of Kuaotunu 
Peninsula or the Manaia and Te Kouma headlands, present a decidedly barren appearance, and little 
or no soil overlies the disintegrated rock. 

Propylitic alteration of the " Second Period " volcanics is confined in the main to certain areas 
of the south-eastern part of the subdivision, and these and other minor areas will receive further refer- 
ence in connection with the quartz veins. 

Character of the Matrix, and Phenocrysts. — The different types of matrix described in connection 
with the volcanics of the " First Period " are also those which mark the rocks at present under con- 
sideration. The hyalopilitic type, however, which was of very infrequent occurrence in the rocks of 
the older series, here becomes the most characteristic, whereas in a great many rocks the matrix 
is what may be termed obscurely micropcecilitic. In addition to the types mentioned, the micro- 
crystalline and finely crystalline groundmasses are also represented. The phenocrysts and their altera- 
tion-products are the same as those detailed in connection with the older volcanics. The types of plagio- 
clases of the most common occurrence are andesii.e and an acid type of labradorite. The crystals are 
often very well preserved, and are on the whole much fresher than in the older rocks ; but they fre- 
quently show corrosion by the glassy groundmass, and contain inclusions of dirty-brownish glass, some- 
times arranged zonally. 

Of the ferro-magnesian minerals hypersthene is again the most abundant ; augite is a common 
constituent, but is rarely dominant ; hornblende is on the whole much better preserved than in the 
older rocks, and is of more widespread occurrence. 

Quartz as a phenocryst is rarely present, and appears to constitute only a sporadic constituent. 
As in the " First Period " volcanics, a poor demarcation between the andesites and dacites therefore 
obtains in this series. 



81 

Types of Volcanic Rocks of the "Second Period.'''' — The volcanic rocks of the "Second Period." 
on the classification adopted in this bulletin, are separable into the following types :— 
(a.) Hypersthene andesites. 
(b.) Pyroxene andesites. 
(c.) Hornblende andesites. 
(d.) Dacites. 

No hard and fast line, however, separates one type from another, and the position of certain 
rocks in the classification depends largely on the judgment of the observer. 

(a.) Hypersthene Andesite. — Hypersthene andesite constitutes the predominant type of the 
" Second Period " volcanics. The following tabulation sets forth the localities from which the several 
varieties of this rock have been determined, either by Sollas and McKay or by the writers : — 

Hyalopilitic hypersthene andesites occur at — 

Sugar Loaf Headland : As inclusions, of trachytoid appearance, in breccia. 

Kerr Creek (Port Charles) : As dull lithoidal rocks, forming the lava-flows and perhaps dyke, 

between the head of the creek and the coast-line. 
Waikawau- Whangapoua coastal belt : Forming a great part of the breccias and lava-streams 

of the coast-line. 
Te Tutu Volcanic Neck. Materangi Ridge and Bluffs : Constituting lavas, tuffs, breccias, 

and agglomerates. 
Mahakirau River : As lava flows, one mile east of the junction with Waitakatanga Creek. 
Cabbage Bay - Kikowhakarcre coastal belt: As pyroclastic and massive rocks, occasionally 

containing a little hornblende. 
Beeson's Island, Rufnn Peninsula, and Te Kouma - Manaia areas : Forming apparently 

the greater part of the pyroclastic and massive rocks ; a little hornblende is occasionally 

present. 

Micropcecilitic hypersthene andesites occur at — 

Sandy Bay : As basaltic-looking rock in coastal breccias. 

Port Charles Headland : As a columnar lava-stream forming main outer headland ; this 
basaltic-looking rock contains sufficient hornblende to admit of it being termed a horn- 
blende hypersthene andesite. 

Waikawau Whangapoua coastal belt : As trachvtoid and basaltic-looking rocks formjng 
breccias and lava -streams. 

Owera Mine | Whangapoua) : As the only fairly fresh rock obtainable in the locality; 
this lava contains a few minute crystals of hornblende. The propylitic weathered 
rock here rtsembles that of the mine-workings at Eftaterangi and Murphy's Hill rather 
than the andesites of the " First Period " at the Opitonui Mine. 

Miterangi Bluff : As a basalt-like rock, containing a little hornblende and augite. 

Kuaotunu- Mercury Bay Road: As a somewhat weathered rock, occurring at Brown's Camp 
between the Try Fluke Mine and the main saddle. 

South coast-line of Kuaotunu Peninsula, near the mouth of Whauwhau Creek : As rather 
coarse, porphyritic. massive, and pvroclastic rocks — hornblende hypersthene andesites. 

Cabbage Bay to Kikowhakarcre coastal belt, and its continuation forming Ruffin Peninsula : 
Associated with the rocks, having a glassy or hyalopilitic groundmass. 

Special mention should be made in respect to one of these andesites occurring within the Waikawau - 
Whangapoua coastal belt. The exact localitv is the south-west shore-line of Kennedy's Bay, where 
the breccias afford fragments of one of the most singular volcanic rocks of the whole subdivision. 
Sollas, who has determined the specimen as a hornblende hvpersthene andesite, pronounces it a " flow 
breccia." The phenocrysts are " brecciated and displaced in a remarkable fashion, .... having 
been reduced to small. angular fragments, which have been carried along with the flow and distributed 
in stream-lines, thus giving rise to lenticular streaks in which feldspar predominates, since, as usual, 
(5 — Coromandel. 



82 

it was the most abundant phenocryst in the rock." " This example," he adds, " proves the need for 
caution when referring brecciation to subsequent movements of consolidated rock. The present case 
might easily be mistaken for one of ' mylonitisation.' "* In the hand-specimen this flow brecciation 
gives to the rock a peculiar schistose appearance 

A typical hyalopilitic hypersthene andesite, containing an occasional crystal of decomposing horn- 
blende, was collected from the outer end of Beeson's Island, and on analysis gave the following 
result : — 



Silica (Si0 2 ) 
Alumina (A1 2 3 ) 
Ferric oxide (Fe 2 3 ) . . 
Ferrous oxide (FeO) . . 
Manganous oxide (MnO) 
Lime(CaO) .. 
Magnesia (MgO) 
Potassium-oxide (K 2 0) 
Sodium-oxide (Na 2 0) . . 
Titanium-oxide (Ti0 2 ) 
Carbonic anhydride (C0 2 ) 
Water and organic matter 



57-68 
18-84 
4-96 
1-44 
21 
6 05 
400 
215 
216 
0-82 
0-75 
0-90 



Total .. .. .. .. .. .. .. 99-96 

The chemical analysis of an andesite from the breccia-beds at Long Bay, Ruffin Peninsula, may here 
be submitted. (Owing, unfortunately, to the loss of the hand-specimen collected the rock was not 
petrographically determined.) 

Silica (Si0 2 ) .. .. .. .. .. .. 60-40 

Alumina (A1 2 3 ) .. .. .. .. .. 17-84 

Ferric oxide (Fe 2 3 ) . . . . . . . . . 6-40 

Manganous oxide (MnO) . . . . . . . . . . - 05 

Lime (CaO) . . . . . . . . . . . 4-30 

Magnesia (MgO) .. .. .. .. .. 013 

Potassium-oxide (K 2 0) . . . . . . . . . . 1-15 

Sodium-oxide (Na 2 0).. .. .. . .. .. 2-46 

Titanium-oxide (Ti0 2 ) .. .. .. 0-41 

Carbonic anhydride (C0 2 ) . . . . . . . . . . 0-30 

Water and organic matter . . . . . . . . . . ..700 



Total . . . . 100-44 

(b.) Pyroxene Andesites. — The pyroxene andesites are not of very common occurrence among the 
volcanics of the " Second Period," since augite, while present to a minor extent in almost all the rocks, 
rarely becomes as abundant as hypersthene. 

The general appearance of these rocks and the characters of the groundmass are the same as those 
of the hypersthene andesites. On the eastern side of the peninsula, pyroxene andesites have been 
collected from Waihirere Creek and from the coast-line two and a half miles southward, both localities 
being within the Waikawau - Kennedy's Bay coastal belt. An altered pyroxene andesite from Mate- 
rangi Hill, Kuaotunu, has been identified by Sollas, and a similar rock from the Otanguru Creek 
by the writers. Further south occurrences of pyroxene andesites at Wade Creek (Mahakirau 
Valley), and in the Kaimarama River about a mile from its junction with the Mahakirau, may be 
mentioned. 

* " Rocks of Cape Colville Peninsula," vol. ii, 1906, p. 142. 



PLATE XXV. 




Hornblende Da< ite, Tertiart Volcanic Rocks of Second Period, South Sum; of Cabbage Bai 
Magnification, 50 diameters. Work of Mr. Alexandei McKay, F.G S 



Geo. Hull No. ; ] 



To fact p. 



PLATE XXVI. 




Htalofilitic Hypersthene Andesite, Tertiary Volcanic Rocks of Second Period, North Side 

of Manaia Harbour. 

Magnification, 33 diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Bvll. No. ',.\ 



[To face f. 



83 

In the vicinity of the western coast-line, the only rock determined which should be included under 
the present heading was a glassy andesite collected from the breccias a short distance to the south of 
Cabbage Bay. 

(c.) Hornblende Andesites. — Hornblende andesites have a fairly wide range within the areas of the 
" Second Period " volcanics, both as pyroclastic and massive rocks. The amphibole, however, is a 
characteristic mineral of many of the intrusions of this period, and, as already stated, it is not possible 
to discriminate in every case between lava-flows and dykes. 

The localities where these rocks have been identified either by Sollas and McKay or by the writers 
may be submitted. 

Hyalofilitic hornblende andesites occur at — 

Sugar Loaf Headland (Moehau Survey District) : As inclusions of trachytoid appearance in the 
breccias. 

Port Charles - Kennedy's Bay coastal belt : As finely textured basalt-like rocks, or coarsely 
porphyritic rocks with a dull lithoidal groundmass. in the flows or pyroclastics on the 
coast-line ; as similar rocks in the valley of Pakore Creek, entering Kennedy's Bay on its 
south side. 

Hill between Kikowhakarere Bay and Kapanga Mine (Coromandel) : As a grey medium- 
grained rock with conspicuous feldspar phenocrysts — hypersthenc hornblende andesite. 
The hornblende andesites extend from here southward, forming the coarse breccias of 
Dacre Hills, and eastward probably to the vicinity of the Blagrove's Freehold Mine. 

M icrofcecilit ic hornblende andesites occur at — 

Poil Charles - Kennedy's Bay coastal belt : In same localities as does the hyalopilitic type. 
Owera Creek (Whangapoua) : Near its headwaters, as a dark-coloured rock with small pheno- 

ciysts, forming lava-fi 
Kuaotunu - Mercury Bay Road, just beyond Brown's Camp : as a greyish-blue basalt-like 

rock — hvpersthene hornblende andesite. 
Waitaia Bay (southern shore-line of Kuaotunu Peninsula) : 4s a coarsely porphyritic rock 

with groundmass approaching the micro-crystalline structure. 
Hooker Creek (Mahakirau) : As dark massive rocks, near the contact of the series with the 

more decomposed volcanics ol the " First Period." 
Branch Creek (Cabbage Bay) : A- dark lava-flow- in the vicinity of the sandy marls of the 

Torehine Series ; groundmass is obscurely micropcecilitic. 

((/ ) Dacites. Rocks collected from three localities within the areas of the "Second Period" 
volcanics have been pronounced as dacites by Sollas. 

On the eastern side ol the subdivision the stratified tuffs from the western spur of Materangi Bluff, 
and the altered rock from the Murphv's Hill mine-workings (both vein-bearing localities of the Kuao- 
tunu Peninsula), have been designated " hornblende dacites." The other occurrence is on the western 
side of the subdivision, near the southern shores of Cabbage Bay, where the volcanics are exposed, in 
the road-cuttings, overlying the old Bedimentaries. 



(3.) TERTIAKY VOLCANIC ROCKS OF THE "THIRD PERIOD." 

General Statement. 
The volcanic rocks of the "Third Period" (Pliocene '). in contradistinction to the greater bulk 
of the older volcanics, are of acidic character. They consist of pyroclastics — pumiceous tuffs, breccias, 
and fine-grained agglomerates — through which have been extruded flows of spherulitic rhyolite. 

These " Third Period " volcan'cs are confined to the south-eastern portion of the subdivision, 
where they form the whole area lyiug to the east of the Whitianga Estuary. This area, differing in 
geological character from the surrounding countrv, presents special physiographic features, which have 
been described in an earlier chapter. 
6* — Coromandel, 



K4 

Age. 

The age of the " Third Period " volcanics cannot be deduced from any evidence afforded 
within the area under review. These rhyolites must, however, be considered as overlying uncomform- 
ably the andesites of the " Second Period " or Beeson's Island Series, dthough actual contacts of the 
rocks have not been observed. The pumiceous agglomerates contain in places small fragments of 
semi-basic volcanics, such as might have been derived from the Beeson's Island Series ; on the other 
hand, the breccias of the latter series, in the vicinity of Whitianga, have never been found to contain 
fragments of rhyolitic material. 

The relationship of these Hauraki rhyolites to those which cover such a large area in the central 
part of the North Island has been discussed by the previous investigators, who were familiar with 
the occurrences in both localities. Park, who considered that the first eruptions of rhyolite 
in the King-country (central part of North Island) should be referred to the Lower Pliocene 
period, writes, " The rhyolitic flows of the eastern Hauraki Goldfields are directly connected, and 
apparently contemporaneous, with those forming the great acidic plateau of the King-country ; the 
author is therefore of opinion that they are of the same age."* McKay, although affirming that this 
acidic group as developed on the Cape Colville Peninsula must be regarded as belonging to the Pliocene 
period, remarks, " Having regard to their connection or otherwise with the acidic group of rocks 
developed in the central region of the North Island around Rotorua and thence extending to Tongariro 
and Ruapehu, those of the Cape Colville Peninsula cannot be regarded other than as older, and uncon- 
formably older, than the pumiceous deposits of the Upper Waitoa Plain, and the extensions of the same 
rocks to the southward "f (i.e., to the central region of the North Island). 

Opinions therefore differ as to correlation of the acidic rocks of the Cape Colville Peninsula with at 
least certain members of the acidic series of the central portion of the North Island. These rhyolitic 
rocks of the Coromandel subdivision have, however, by all previous investigators been regarded as 
Pliocene, and this opinion is shared by the writers of the present bulletin. 

Distribution. 

The volcanic rocks of the " Third Period " are, as already stated, confined to the south- 
eastern part of the subdivision. The major area, which covers some twenty-two square miles, 
is that lying to the eastward of the Whitianga Estuary. To the westward of this physical feature 
an area of about one square mile, lying to the south of Kaimarama River and including Trigonometrical 
Station V, consists of these rocks ; so also does a very small inlier known as Trelease's Point, lying to the 
north of the Kaimarama. 

Structure, and Conditions of Eruption. 

The oldest rocks of this period,' which appear in the subdivision, are the pyroclastics. They 
are disposed, in the main, as horizontal or nearly horizontal beds, but occasionally small patches 
are inclined at fairly high angles. These pyroclastics pass beneath the low-tide mark, or below the 
alluvial flats, and nowhere is exposed the basement or older rock upon which they rest. The total 
thickness of thes'^ accumulations is therefore unknown, but the height above sea-level attained by the beds, 
notwithstanding denudation, still exceeds 500 ft. in places. Jointing is occasionally well marked, and 
in the case of the harder rocks affords sharply cut cuboidal blocks. Other cliff-faces of pumiceous tuff 
or fine-grained agglomerate, which are bare and exposed for over 100 ft. in vertical height, exhibit 
scarcely a single joint, and in such localities it is not uncommon to see a cliff undercut some 20 ft. at its 
base, without showing the slightest signs of collapse. 

There is little evidence bearing on the conditions under which these pumiceous agglomerates were 
erupted. Small included fragments of semi-basic rocks probably represent the shattering of the older 
andesitic rocks, through which the rhyolites were extruded. The character of some of the finer-grained 



; Geology and Veins of the Hauraki Goldfields," 1897, p. 40. t c -~ 9 > 1897 > P- 68 . 



85 

tufaceous rocks, and the planes of stratification and current bedding, which are often present, suggest 
accumulation under subaqueous conditions ; so also does a thin band of stratified gravel separating 
beds of these fragmentals near the north-eastern headland of Whitianga Harbour. Other portions 
have the appearance of deposition under subaerial conditions. 

Extruded through the pyroclastic rocks described, and capping them in many places, are massive 
rhyolites, generally showing fluxion-banding and spherulitic structure. These rocks, owing partly 
to their superposition in the series, partly to the greater resistance they offer to weathering agencies, 
form the higher hills of the dissected plateau-like country extending from the Whitianga Estuary to the 
eastern coast-line. The massive rhyolites are in places highly silieified, and have associated with them 
deposits of siliceous sinters, forming mounds and " shoadings " on the crests of some of the hills. These 
mounds mark the sites of extinct hot silica-bearing springs. In this connection the existing hot springs 
of Wigmore Creek and Hot Water Beach, which lie within the rhyolitic area, are significant, although 
the amount of sihca contained in these waters is relatively small. 



Petrology. 

General Statement. — The " Third Period " volcanics, as previously indicated, consist of pumiceous 
pyroclastic rocks and massive rhyolites. 

The pyroclastic rocks, which are all pumiceous, comprise hue-grained Sandy tuffs, with minor beds 
of tufaceous mudstones, fine-grained agglomerates, and hue- and coarse-grained breccias. The massive 
rocks consist wholly of banded and spherulitic rhyolites. Fragments of black volcanic glass, or ob- 
sidian, are in places of fairly common occurrence in the surface debris. This rock was not detected 
in situ, but probably occurs as fragments in certain beds of the pumiceous fragment, il rocks. 

Pumiceous Tuffs. — The rocks here considered, under the heading of pumiceous tuffs, vary from a 
white or cream-coloured ashy-looking rock to a drab-coloured rock of rather earthy appearance. The 
former consists in the main of white fine-grained pumiceous material, with minute dark specks of flow 
rhyolite and foreign material. It is rather easily pulverised, and affords a soft chalky powder with 
which is associated a little fine grit. This light-coloured rock is well exhibited in the*aliuost vertical 
cliffs of Whitianga Rock on the east side of Whitianga Estuary, also in Shakespeare Cliff, and else- 
where. These white walls of rock, with their vertical flirtings or corrugations, recall similar features 
in limestone country, and their remarkable resemblance to cliffs of Oamaru limestone and certain cal- 
careous sandstones in both Islands of New Zealand has been noted by McKay.* The drab-coloured 
earthy rock is in general similar in mineralogical composition to the white tufaceous rock described, 
but is of slightly coarser texture, and resembles more a tufaceous sandstone. This rock has its typical 
development just to the south of " Whitianga Rock," where it occurs in the cliffa bordering the harbour. 
The rock has a uniform massive appearance, and on the application of an explosive splits readily into 
large slabs. 

A peculiar characteristic of both the white ashy tuff and the drab-coloured earthy tuft is the thin 
hard siliceous "skin" or segregation which is found to coat their exposed weathered surfaces. This 
siliceous coating affords an effective barrier to the further progress of weatht ring action on what is 
otherwise a soft rock. The slow recession of the cliffs from the shore-line is, therefore, caused rather 
by undercutting due to marine erosion, and the consequent collapse of the superstructure, than by a 
general weathering of the cliff-faces. 

PvnticetWS Agglomerates. — What may be termed a pumiceous fine-grained' agglomerate is the 
most widespread and characteristic of the pyroclastic rocks of this series. The general mass of this lock 
is white or cream-coloured, and consists of fine-grained pumiceous material interspersed with small 
subangular and rounded fragments of dark massive rhyolite, and occasionally of semi-basic igneous 
rocks. These rocks on weathering present similar features to those already described, but the small 
inclusions of hard massive lavas, as well as of pumice, give rise to rather rough surfaces. 



* C.-y, 1*:>7, p. 0-t. 



86 

Under the microscope a section of this rock, collected from a point south of the particular area 
under review, has been described by Sollas.* The matrix consists of fragments of pumiceous colour- 
less glass and greenish granular material. The included fragments comprise pumice, chiefly of colourless 
glass ; micro-spherulitic rhyolite ; fragmentary spherulites ; black and colourless glass (the former red- 
dish brown by reflected light) : How rock, composed of ragged feldspar laths and tridymite : magnetite 
grains, ochreous dust, plagioclase phenocrysts, and broken crystals of hypersthene, hornblende, and 
augite, &c. Plate XXVII is a fair representation of this rock under magnification of 20 diameters 
in ordinary light. 

This fine-grained agglomerate has considerable development throughout the area lying to the 
east of Whitianga Harbour, and forms the small inlier, Trelease's Point, on the western side of this 
arm of the sea. 

Pumiceous Breccias. — A rock which may be classed as a pumiceous breccia is composed of yellowish- 
grey, dark-grey, and white fragments in a faint-pinkish-grey-coloured matrix. The majority of these 
fragments are about Jin., but occasionally exceed 1 in., in largest dimensions, and often show a more 
or less definite alignment, suggestive of flow structure. Some of this rock shows lenticular flake-like 
fragments and shreds of dark-brown glassy material. These, as seen in the rock in situ, are approxi- 
mately horizontal, and at times exceed 3 in. in length. 

Under the microscope the rock proves to consist mainly of tuff-like fragments of glass, in part 
of a brownish colour, and somewhat granular (ultra-microscopic), in part colourless and pumiceous with 
bands and specks of dark dusty material. Scattered throughout this matrix are fragments and fairly 
complete crystals of plagioclase. showing little lamellar twinning (r.i. above balsam) : orthoclase ; 
pieces of finely banded rhyolite ; and fragments of the groundmass of flow rocks. Any quartz 
that may have been present has been torn out of the soft rock in the process of grinding the section. 

An alignment of most of the pumiceous fragments and other constituents, as well as the fluxional 
arrangement of some of the glass, is conspicuous, and gives one the impression that the accumulation 
of ash prior to final consolidation had been subjected to movement simulating the flow of a lava-stream. 

Some of this rock, and particularly that occurring on the outer portion of the eastern headland 
of Whitianga Harbour, has at least a partial resemblance to the so-called " wilsonite " of Waihi, 
Waitekauri, and Waikino, in the southern part of the Hauraki Division.! The section made from the 
Whitianga rock, however, exhibits a much less well-defined flow structure than does the " wilsonite " 
of the localities cited, and without further investigation the identity of the rocks cannot be claimed. 

These types of pumiceous breccia form the greater part of the headland lying to the north of the 
Ferry Pier, on the east side of Whitianga Harbour, and a somewhat similar rock forms the hills on the 
west side of the harbour in the vicinity of Trigonometrical Station V. Eeference will be made later to 
the value of this stone for building purposes. 

Coarse-grained breccias form only a few beds of inconsiderable thickness within the subdivision. 
They are occasionally seen in the cliffs of the coast-line, and generally occupy low horizons in these 
bedded fragment als. Mineral ogically they do not differ from some of the finer-grained pyroclastics 
already described. 

Banded and Spherulitic Rhyolites. — Massive rhvolites. although abundant in the area under descrip- 
tion, are all in such an advanced state of surface decomposition that it is difficult to obtain even fairly 
fresh specimens. The prevailing rock appears to be a pinkish-grey rhyolite consisting almost entirely 
of spherulites, ranging from £ in. in diameter down to microscopic dimensions, with small glistening 
hexagonal and irregularly shaped flakes of biotite. A few small crystals of quartz and feldspar are 
also visible. Sections of the rock under the microscope show a mass of closely compressed spheru- 
lites of smoky-brown colour, which only feebly transmit light between crossed nicols. Plates of deep- 
brown strongly pleochroic biotite, grains and small crystals of quartz, plagioclase, and orthoclase, 
are interspersed throughout the spherulitic mass. 

* " Rocks of Cape Colville Peninsula." vol. i. 1005, p. 220. t Loc. cit, vol. i. 1905, pp. 123, 124. 



PLATE XXVII. 




%k 



> 




u - ^ 









h J * 




:'• 


\ - 





Pdmiceous Fine-grained Agglomerate, Tertiary Volcanic Rocks of Tiiihd Period, as at 

Will TI \N<;.\. 

Magnification, l ;| J diameters. Work of Mr. Alexander McKay, F.G.S. 



Geo. Bull. No. ; • 



[To face p. 86. 



87 



An analysis of this rhyolite resulted as follows : — 
Silica (Si0 2 ).. 
Alumina (A1,0 3 ) 
Ferric oxide (Fe 2 3 ) 
Ferrous oxide (FeO) 
Manganous oxide (MnO) 
Lime (CaO) 
Magnesia (MgO) 
Potassium -oxide (K 2 0) 
Sodium-oxide (Na 2 <>) 
Titanium-oxide (Ti0 2 ) 
Carbonic anhydride (CO 2 ) 
Water and organic matter 

Total 



7240 
1409 
048 
2-52 
042 
115 
020 
4-09 
2-97 
015 
0-82 
0-86 



..10015 
The banded rhyolites show a similar mineralogies] composition to those just described, but the 

spherulites attain much greater dimensions, sometimes exc ling 1 in. in diameter. Bands in which 

the larger spherulites, or more frequently the spherical cavities formed by the decomposition of the 
spherulites, predominate, are found alternating with hands showing a finely laminated structure, the 
laminae being evidently coincident with the fluxion planes. These handed and apherulitic rhyolites 
form most of the higher hills in the central portion of the area between Whitianga Harbour and the 
eastern coast-line, and the whole of the hilly country between Wigmore (reek and Hot Water Beach. 

The fragments of black volcanic glass, to which reference has been made, contain a few small white 
spherulites, and often show lamination due to How. This rock has been described by Park and Kutlev. 
who sav, " Under the microscope, between crossed nicols, it appears to be completely isotropic with 
the exception of one or two brown spherulites." A small crystal of plagioclase, containing a prism or 
two of apatite, is enclosed in one of these spherulites : epidotc is another mineral which has been 
detected as minute crystals. " In ordinary transmitted light the section is seen to contain numerous 
trichites and longulites, the latter especially as a rule forming narrow hands in the cbrection of flow. A 
few globulites are also present."* 



(4.) INTRISIVE BOCKS OF VARIOUS PERIODS. 
General Statement. 
Intrusive igneous rocks, representing apparently a considerable range in time, are largely developed 

within the Coromandel subdivision. They are found associated with each of the series of sedimentary 
rocks already described, and with the Tertiarv effusive rocks of the " First " and the "Second Period," 
which overlie these sedimeiitaries. 

Considered from the chemical point of view, these intrusive, fall into two classes — (a) the semi- 
basic and (6) the acidic. The former class is represented by diorites, porphvrites, dacites, and 
andesites, occurring in considerable abundance, while the latter is represented only by rhyolites existing 
in two separate localities. 



(a.) The Semi-basic Intrusives. 

General Distribution. 

The great abundance of semi-hasic dykes and sills associated with the rocks of the Tokatea Hill 
Sene> is characteristic of all areas in which these old stratified rocks are developed. The small inlier 
of this series in Whaiwango (Big Paul's) Creek the major belt extending from north of Tokatea Hill to 



* Q.J.G.S., 189!», vol. lv, p. 4.">:i. 



88 

the Tiki Creek, and the area within the Manaia Valley are marked by an abundance of intrusives, 
particularly hornblende porphyrites. 

The strata of the Moehau Series, more or less throughout their whole extent, but more particularly 
in certain localities, are intruded by sen^i-basic dykes and sills. The locality especially characterized 
by these irruptives is that of the western flanks of Moehau Range, where a considerable area consists 
entirely of diorites, porphyrites, dacites, and andesites presenting considerable petrographical variety. 
The relative paucity of intrusives associated with the comparatively extensive belts of the Manaia 
Hill Series on both sides of the main divide is rather pronounced. 

The igneous rocks intruding the Manaia Hill Series, moreover, exhibit a nearer approach to the 
andesitic facies than do the greater number of those associated with the older groups of sedimentaries * 

Definitely ascertained dykes are not numerous in association with the volcanics of the " First 
Period." Mining operations have, however, revealed the existence of intrusives in certain localities 
where no signs of such are recognisable at the surface. The close similarity of the weathered products 
of both the effusive and the dyke rocks, together with the heavy overmantle of debris which almost 
everywhere covers the country, sufficiently accounts for the fewness of the intrusives detected in these 
andesitic areas. By far the most conspicuous dyke intersecting these volcanics is that forming Castle 
Rock, Motutere, &c, on the crest of the main divide. This rock is a hornblende hypersthene dacite. 

Intrusives intersecting the volcanics of the " Second Period " are by no means uncommon, but, being 
generally andesitic, are often not to be distinguished with certainty from the lava-flows. The ascertained 
dykes in these rocks are mostly exhibited in the steep cliffs and marine shelves of the coast-line ; else- 
where there obtain conditions somewhat similar to those noticed in connection with the older volcanics. 
and render the detection of dyke rocks difficult. 

Age. 

As demonstrated in previous sections of this chapter, a Tertiary age can with certainty be 
assigned to the great pile of effusive rocks which have been extruded through, and rest upon, the base- 
ment sedimentaries of the area under review. Certain outliers of andesitic lavas and breccias, parti- 
cularly the one found near the very crest of Te Moehau Mountain, further suggest that the Tertiary 
effusives formerly covered a very much greater area of the sedimentary rocks than they do at present. 
A large number of dykes and sills are now exposed on the denuded and worn-down surface of the base 
ment folded complex, more especially in that part of it consisting of the Tokatea Hill Series and the 
Moehau Series. It is reasonable to infer that some of these irruptives are the hypabyssal analogues of 
the Tertiary effusive rocks, which formerly existed in these particular localities. Others, again, are 
probably coeval in age with the dykes which are found intruding, in other localities, these " First " 
and " Second Period " effusives. 

While many of the dykes and sills associated with the Tokatea Hill and Moehau rocks are doubt- 
less of Tertiary age, there is sufficient evidence to conclude that some are of considerably greater antiquity. 
The facts upon which this conclusion is based may be briefly narrated : (a.) The Jurassic rocks (Manaia 
Hill Series) contain remarkably few intrusives, even where these strata lie immediately adjacent to the 
areas of the Tokatea Hill Series (Pre- Jurassic), crowded with dykes and sills. (Compare conditions in 
Matawai and Tiki Creeks, page 41.) (6.) The fine grained Jurassic conglomerates contain bands or 
pebble-beds, in which occur well-rounded boulders of igneous rocks, ranging up to 2 in. in diameter. 
These boulders show a strong lithological resemblance to the dyke rocks intruding the Pre-Jurassic 
sediments (Tokatea Hill and Moehau Series), and were probably derived from these or other intrusives 
coeval in age with them. This seems the only possible explanation which will account for these fairly 
large, and therefore locally derived, boulders, (c.) The occurrence of holocrystalline rocks, as intrusives 
in the Moehau Series, is significant. These holocrystalline rocks, which occur on the. western slopes of 
Moehau Range and extend to its actual crest, may reasonably be considered to have consolidated 



* Though, according to many penologists, it is desirable to employ separate names for dykes and other 
intrusive rocks, the writers found that many occurrences of the rocks in the Coromandel subdivision coming under the 
heading of intrusives showed no distinctive points of difference from ordinary volcanic rocks, and therefore they con- 
sidered it inadvisable to make use of names which would imply different characters. On the other hand, certain 
intrusives presented all the characteristics of diorite, and that name has therefore been retained for such rocks. 



89 

at some considerable depth. Since a small outlier of effusive andesites, as already mentioned, is still 
preserved near the summit of Te Moehau Mountain, no very great thickness of sedimentary rock can 
have been removed by denudation since early Tertiary times. The diorite was therefore probably 
intruded into the sedimentaries, and subsequently exposed or partly exposed by denudation, prior to 
the manifestations of Tertiary vulcanism. That the diorite is of greater age than at least some of the 
andesites is proved by an occurrence in Sorry Mary Creek. The light-grey diorife, exposed in this 
creek-bed at about 25 chains from the mouth, is intersected by a small dyke of dark pyroxene andesite, 
the two rocks presenting a rather marked contrast in the relative states of their preservation. No 
diorites or diorite porphyrites have been detected intruding the Jurassic strata (Manaia Hill Series). 
Andesite and to a lesser extent porphyrite, the latter rock ge erally showing an approach to the ande- 
sitic facies. constitute the comparatively few dykes that do occur in these beds. 

It would appear from the above considerations that the rocks of the Tokatea Hill and Moehau 
Series were intruded by semi-basic igneous rocks prior to the deposition of the Manaia Hill Series. 
Contemporaneous with the extrusion of the Tertiary volcanics, these old sedimentaries, and with them 
the vounger Manaia Hill Series, were again intruded by igneous rocks. 

On account of the general similarity in chemical composition of the older and younger intrusives, 
it is impossible to separate them. but. as already suggested, some of the more crystalline of these irrup- 
tives are probably referable to a Pre-Jurassic age, while most of the Less crystalline are Tertiary. The 
area affords no evidence by means of which the age of the Pre-Jurassic intrusives may be fixed more 
definitely. 

The actual period of intrusion of the various semi-basic dykes that have been recognised in associa- 
tion with the Tertiary effusive rocks is a matter of lesser interest, and, while necessarily younger than 
the actual volcanic accumulations in which they occur, there are few criteria by which their age can be 
more close 'v determined. It would appear that the latter part of the " Second Period " (Miocene *.) was 
especially characterized by the intrusion of dyke rocks into the consolidated or partially consolidated 
volcanic accumulations. The greater alteration, however, of the earlier intrusives in the volcanics, and 
the consequent failure to recognise many of them, must, id this connection, not be overlooked. Some 
of the previous investigators in this district have ascribed a Miocene age to the great Castle Rock dyke 
which intersects the volcanics of the " First Period," but, while this may be correct, it cannot be 
affirmed with any degree of certainty. 

Petrology. 

The semi-basic intrusives consist of quartz-biotite diorite. quartz diorite. diorite porphyrite, horn- 
blende porphyrite, pyroxene porphyrite, dacites, aud hornblende-, h\ persthene-, and pyroxene-ande- 
sites. Many of the dyke rocks are so much altered that they do not admit of definite classification, 
and can only be described as altered porphyrites, altered andesites, &<•., but these are doubtless refer- 
able to one or other of the above tvi 

Quartz-biotite Diorite. — The quartz-biotite diorite is of both economic importance and petrographical 
interest. It is a grey-coloured granite-like rock, showing megascopically white feldspar, greenish- 
black biotite, and other ferro-magnesian minerals of medium grain. A little pyrite is sparsely distri- 
buted throughout some specimens. Under the microscope* the rock is observed to be holocrystalline, 
with the hypidiomorphic granular structure. The feldspars are dispersed as numerous opposed crystals, 
the interstices between the crystals being filled with quartz. Zonal structure and twinning on the 
albite, pericline, and Carlsbad plans are all observable. Minute crystals of augite and hypersthene 
occur as inclusions in the feldspar. Separated by specific gravitv the principal feldspar is found to be 
andesine (s.g. 2-675), but some labradorite (s.g. 2-74) is present, and a little orthoclase (s.g. 2-547). 
Quartz is interstitial or occurs as large grains containing irregular liquid-cavities with bubbles, also 
belonite-like crystallites. Biotite forms fairly large corroded crystals with apatite inclusions, and 
acquires a greenish colour on weathering. In association with the biotite is hornblende as greenish 
corroded crystals, often showing twiiming. Magnetite, ilmenite, and sphene constitute the minor 



* Microscopic details which follow are those given in " Rocks of Cape Colville Peninsula," vol. i, 1905. p. 264. 



90 



accessories. The minerals of the rock weiv separated and quantitatively estimated (by Sollas), with 
the following result :— 

" Orthoclase . . . . ... 

Andesine (formula Al 2 An t ) .. 

Biotitc 

Hornblende 

Quartz (including feldspar of sp. gr. 2-65) 

Magnetite 

Zircons, &c. 

100-0 " 
A specimen of this diorite collected by the writers was submitted to chemical analysis, the result 
being as under : — 

Silica (Si0 2 ) . . . . . . . . . . . . . . 57-32 



Per Cent 


3-8 


51-6 


211 


4-8 


170 


11 


0-6 



Alumina (A1 2 3 ) 
Ferric oxide (Fe 2 3 ) 
Ferrous oxide (FeO) 
Manganous oxide (MnO) 
Lime (CaO) 
Magnesia (MgO) 
Potassium-oxide (K.,0) 
Sodium-oxide (Na.,0) 
Titanium-oxide (TiO.,) 
Carbonic anhydride (C0 2 ) 
Water and organic matter 



17-69 
2-24 
5-62 
0-21 
6-50 
3-66 
1-25 
404 
0.85 
0-67 
013 



100-18 
The percentage of silica (57-32) is rather low for a rock of the quartz diorite class, and the chemical 

analysis agrees more closely with those of normal diorites. The rock has considerable development on 

the western slopes of Moehau Range, particularly in the spur which terminates at the sea-border 

some 60 chains north of Darkie Creek. 

The suitability of this rock as a building-stone is discussed in another section of this chapter 

(see page 96). 

Quartz Diorite. — The quartz diorite is somewhat similar in megascopic appearance to the type just 
described. Under the microscope this holocrystalline rock consists of plagioclase (extinction angles up 
to 30°), greenish hornblende partly derived from pyroxene (uralite), and interstitial quartz showing 
micrographic intergrowths. Biotite is absent. The minor accessories are ilmeiute and apatite. 

This quartz diorite has considerable development in Ohinewai and Darkie Creeks, on the western 
flanks of Moehau Range. It is often considerably altered and pyritised, and neither the extent of the 
intrusions, nor their relationship to the other types of the igneous rocks existent in the vicinity, is 
apparent. 

Diorite Porphyrite.— Intrusive rocks exhibiting phases of gradation between the diorites just 
described and the porphyrites to be next considered, are not uncommon. A type which may be de- 
signated a quartz-biotite-diorite-porphyrite occurs near the head of Ohinewai Creek and also near the 
coast-line between this creek and the Ongahi Creek. Rocks designated by Sollas " quartz-biotite-diorite- 
porphyrite " and " quartz - augite diorite porphyrite " were collected by McKay from the boulder 
banks of the coast-line near the mouth of Waiaro Creek, and evidently have been derived from the 
western spurs of Te Moehau. 

Hornblende Porphyrites. — Under the heading of hornblende porphyrites, has been grouped a 
widespread series of dyke rocks, in which hornblende is, or has been, the dominant ferro-magnesiau 
mineral. They may be regarded as standing between the diorites on the one hand and the dacites 



PLATE XXVIII. 




Quaktz Diorite, Dtke Rock, Westebk Slope Ti: Moehad Mountain. 
Magnification, 00 diameters. Work of Mr. Alexander McKay, F.G - 



Geo. Bull. No. .',.] 



[To face />. 90. 



91 

and andesites on the other. These rocks, which vary from light grey to dark grey in colour, have the 
porphyritic structure characteristic of this particular class. The matrix in which the phenocrysts are 
set varies from micropoecilitic to almost granitic, and is sometimes abundant, or again constitutes a 
relatively small proportion of the rock. 

The plagioclases, which show the usual zonal structure, twinning lamellse, and inclusions, vary 
in the main from andesine to acid labradorite. The pleochroic hornblende of yellowish to greenish 
colour with resorption borders, usually shows considerable alteration, as in the effusive andesites. Augite 
and hypersthene are occasionally present as subsidiary constituents. Quartz, to a lesser or greater extent. 
occurs in all these porphyrites, either interstitial or as small medium-sized grains with various inclusions. 
The minor accessories are magnetite, ilmenite. apatite, and zircons. The alteration-products of these 
primary mineral constituents do not differ materially from those occurring in the effusive rocks. Having 
regard to the quartz-content of these rocks. Professor Sollas has termed many of them "hornblende 
dacite porphyrites." While, however, some of these porphyrites have their less crystalline analogues 
in the dacites, others may reasonably be supposed to represent the hypabyssal equivalents ol the 
more pn dominant effusive rocks — namely, andesites — so that the more general term "hornblende 
porphvrite " has been preferred in this bulletin. 

Hornblende porphyrites or altered porphyrites, in which hornblende was probably the dominant 
ferro-magnesian constituent, have been identified as occurring at the following localities : — 

(a.) As dykes or sills in the Tokatea Hill Series : — 

Whaiwango (Big Paul's) Creek : Dykes appear in both branches, close to the main junction. 
Harataunga Stream, in the branch following closely the Tokatea Kennedy's Bay Road : 

Dyke occurs at first waterfall seen on descending this road From the Tokatea Saddle. 

Tokatea Hill, in No. 7 level of the Royal Oak (Tokatea) Mine : |)\ k. occurs a( 1,600 ft. from 
the mouth of level. 

Petote Creek : Dykes considerably altered are exposed in the creek-bed at various in- 
tervals. 

Tiki Creek, and its tributary the Pukewhau : Dykes occur at frequent intervals ; some 
may correspond with those exposed in Petote Creek. 

Matawai Creek : Dykes occur in bed of main right-hand branch, within half a mile of 
Opitonui Saddle. 

Manaia River : Numerous dykes, sills, and plugs are conspicuous in both main branches ; 
* many of the rocks, however, are considerably altered. 
(b.) As dykes or sills in the Moehau Series : — 

Coast-line 10 chains north of the mouth of Kantail Creek (Moehau Survey District). 

Moehau Mountain, on the actual summit, and extending for some 30 chains to the north- 
west. 

Sorry Mary Creek, 20 chains from the coast-line (altered rock). 

Hope Creek: Main exposure, 20 chains wide, about half a mile from coast -line, smaller 
exposures higher up the creek, 
(c.) As dykes or sills in the Manaia Hill Series : — 

Whareroa Creek (Kennedy's Bay) ; Intrusives, considerably altered, occurring just below 
the first main junction above the Huakitoetoe junction. 
(d.) As dykes intersecting the volcanics of the " First Period " : — 

Golden Pah Mine (Coromandel) : Forming a hard bar in workings, and probablv extending 
into the Union Beach section of the Hauraki Mine. 

Maiden Mine (Opitonui) : A rock collected by McKay from tip-head ; probablv forms a 
dyke in the mine- workings.* 
(e.) As dykes intersecting the volcanics of the " Second Period " : — 

Otanguru Creek, in left-branch about 16 chains above the main junction. 

Howell Creek (Mahakirau), near head. 



" Rocks of Cape Colville Peninsula," vol. i, 1905, p. 206. 



92 

Pyroxene Porphyrite. — The pyroxene porphyrites, which are of comparatively rare occurrence, are 
closely related to the hornblende porphyrites, the pyroxenes, which are frequent accessory minerals 
in the latter type, having in this case become the dominant coloured elements. A specimen of a pyroxene 
porphyrite from the western coast-line in Moehan Survey District shows a few ragged plates of deeply 
pleochroic biotite. A somewhat similar rock constitutes the dyke in the Manaia Hill Series at the 
junction of the Taurarahi Creek with the Manaia. 

Rocks in which pyroxene was originally the dominant ferro-magnesian constituent are the com- 
paratively rare uralite porphyrites. These generally contain fairly large grains of quartz. Uralite 
porphyrite has been identified by Sollas as forming a dyke in the main branch of Tiki Creek, and another 
in Cadman Creek. 

The Dacites. — The dacites occurring as intrusives usually vary in colour from light grey to dark grey 
or almost black, and show small phenocrysts of feldspar and ferro-magnesian minerals. Under the 
microscope they are seen to differ little from the effusive dacites, excepting in the nearer approach 
to the crystalline structure in the groundmass. In the great majority of the dacites hornblende is the 
dominant ferro-magnesian mineral. The quartz occurs either in the matrix, as irregularly shaped 
grains sometimes attaining a size comparable with that of the phenocrysts, or less frequently as fairly 
large corroded grains. Most of the rocks show considerable alteration, pyrite in some being fairly 
abundant. 

Rocks determined as dacites have been collected from the following localities : — 

As intrusives in the Tokatea Hill Series : — 

Cadman Creek, not far above the junction with the Petote Creek : Altered dacite (Sollas). 
Tiki Creek, from right or main branch : Hornblende dacite (Sollas). 
Pukewhau Creek (branch of Tiki) : Several intrusions of altered dacite. 

As intrusives in the Moehau Series : — 

Western coast-line (Moehau Survey District), 15 chains north of Fantail Creek : Altered 

hornblende dacite. 
Fantail Creek (Moehau), about one mile from mouth : Hornblende dacite (m.). 
Western coast-line (Moehau Survey District), 17 chains north of Waiaro Creek : Hornblende 

'< % dacite (m.). 
-- — * . 

Boulders from shore-line near mouth of Waiaro Creek (collected by McKay), probably de- 
rived from western flanks of Moehau : Hornblende dacite (Sollas) ; microgranitic dacite 
(Sollas). 

As a dyke in volcanic rocks of the " First Period " : — 

Castle Rock (Motutere), the most conspicuous dyke in the subdivision : A hypersthene horn- 
blende dacite. 

The Andesites.— Intrusive andesites are found associated with the Tokatea Hill, Moehau, Manaia 
Hill, and Torehine Series of stratified rocks, and also with the " First " and " Second Period " volcanics. 
These andesites show the same assemblage of constituent minerals as do those occurring as effusives. 
The micropcecilitic matrix is the most common type, but the hyalopilitic is also represented. The 
following occurrences may be noted: — 

(a.) As intrusives in the Tokatea Hill Series : — 

Altered andesites occur in the headwaters of the Waverley Creek (a tributary of the Hara- 
taunga), in Maddern and Tiki Creeks, and elsewhere. 

(b.) As intrusives in the Moehau Series : — 

They are of fairly common occurrence throughout the whole extent of the Colville and Moehau 

Survey Districts as dykes and sills. Hornblende-, pyroxene , and hypersthene-andesites 

have all been recognised. 

A dyke of pyroxene andesite in Sorry Mary Creek, about 25 chains from the coast-line, should 

be specially mentioned as intersecting the altered dioritic intrusive rock of this locality. 



93 

(c.) As intrusives in the Manaia Hill Series : — 

Western coast-line (Harataunga Survey District), south of the mouth of Tawhetarangi 

Creek : Hypersthene hornblende andesite (h.) (Sollas). 
Waiau River, about a mile and a half above jxuiction of Matawai : A hornblende 

pyroxene andesite (h). 

(d.) As intrusives in the Torehine Series : — 

Omoho Creek, dyke 2 ft. to 3 ft. wide intersecting both Moehau and Torehine Series : An 
altered hypersthene andesite, containing a little hornblende. 

(e.) As intrusives in the volcanics of the " First Period " : — 

Omoho Creek, in gorge below the first exposure of the Torehine Series : Hornblende andesite 

(m.), cutting rhyolitic tuffs. The same dyke appears again in a small left-hand branch 

entering the main creek at the lower part of the gorge, and is still in association with the 

acidic effusive*. 

Wairakau Creek (Harataunga), at the junction of the main headwater branches : Altered 

pyroxene andesite is intrusive in the effusive andesite-. 
Maitaiterangi Creek (Harataunga) : Several intrusions of altered hypersthene(?) andesite 

occur in the headwater branches. 
Kopurukaitai Creek (Harataunga). in main creek about 30 chains above junction of Four- 

in-Hand Creek : A belt of hypersthene hornblende andesite is apparently intrusive. 
Trig. Hill (Coromandel), in the shaft of the Kathleen Crown Mine, south-west of Trigono- 
metrical Station E : A dark felsitic-looking rock, much fresher than those of the imme- 
diate vicinity, was encountered. Sollas. who has pronounced it hornblende andesite 
containing quartz in the groundmass, remarks, " The matrix is not pilotaxitic, but a 
minutely crystalline admixture."* This rock, which is probably a dyke in the effusive 
volcanics, gave on analysis the following result : — 

Silica (Si0 2 ) .. .. .. .. .. .. 57-32 

Alumina (A1 2 3 ) . . . . . . 16-56 

Ferric oxide (Fe 2 :! ) .. 9-28 

Manganous oxide (MnO) .. .. .. .. 0-25 

Lime (CaO) • • • . . . . . . . 605 

Magnesia (Mg<>) . . . . . . 01 2 

Potash (Iv.O) .. .. 1 52 

Boda(Na s O] .. .. .. .. .. 2-38 

Titanic oxide (Ti0 2 ) .. .. 048 

Sulphuric anhydride (SO.,) . . . . Nil 

Carbonic anhydride (C0 2 ) . . . . 3-20 

\V.iter*and ? organic , 'matter . . . . 2-50 



99.66 



(/.) As intrusives in the volcanics of the " Second Period.'' 

These, as already remarked, are numerous, but are with difficulty distinguished from the lava- 
streams. When their intrusive character is most apparent their positions have been indicated on the 
maps. These intrusives differ little in lithological character from the effusive rocks already described. 
Two closely associated and conspicuous ribs of rock on the southern shore of Kikowhakarere Bay (Coro- 
mandel) are worthy of notice owing to their proximity to the principal mining-area of the subdivision. 
The lighter-coloured porphyritic rock has been pronounced an altered hornblende dacite,f the quartz 
being confined to the minutely crystalline groundmass. The petrographical description of this rock, 
and of the one occurring in the Kathleen Crown Mine compares very closely, and the intrusives are pro- 
bably identical. 



* Sollas and McKay : " Rocks of Cape Colville Peninsula," vol. i, 1905, p. 140. j- Lot. cit., vol. i, p. 144, No. 2868. 



94 

The other dyke rock, which is a compact basalt-like rock* glistening with feldspar, has been 
designated a hornblende enstatite(?) andesite (m.). 

(b.) Acidic Intrusives. 
General Statement. 

The acidic intrnsives have, in comparison with those of semi-basic character, an inconsiderable 
development within the area of this subdivision. They consist of dykes of rhyolite, which are pro- 
bably referable to a Tertiary age. 

Distribution and Structure. 

Only two rhyolite dykes have been definitely ascertained as existing in this area — namely, one 
on the eastern slopes of Tokatea Hill, within the Harataunga watershed, the other within a head- 
water valley of the Umangawha. 

The former dyke constitutes the conspicuous ridge of white rock that extends nearly due north 
from a point within 4 chains of the Plutus Road to the second waterfall of the creek rising in Tokatea 
Saddle. The Tokatea - Kennedy's Bay Road, which passes close to this waterfall, has been cut through 
the dyke. The further extension of the intrusive northward from this point is not apparent, but it may 
be expected to occur in the vicinity of the Royal Oak battery. This dyke, which ranges from 3 to 
4 chains in width, intersects the stratified rocks of the Tokatea Hill Series, and apparently dips at high 
angles to the westward. The rhyolite, as exposed on the steep face of the south side of the creek at the 
waterfall, exhibits columnar structure, but at a higher elevation on the sharp ridge extending southward 
it shows flow structure on a large scale, thus simulating a lava-stream. In certain localities this white 
rock presents an earthy chalk-like appearance. 

The rhyolitic intrusive in the Umangawha Valley occurs in the main headwater branch of the 
stream, at a point about 90 chains in a straight line from the junction of Branch Creek. The exposure, 
which is a small one, was located on the right-hand side of the creek, and the intrusive appears to be 
associated with the altered acidic tuffs overlying at this point the old sedimentary rocks (Moehau Series). 
It is more than probable that in the rough bush country of the Umangawha Valley, other rhyolitic 
dykes exist in association with the belt of acidic effusive rocks already described. 

Age. 

The age of these rhyolitic dykes may be based on the assumptions that the occurrence in the 
Umangawha is irruptive into the acidic effusives of early Tertiary age, and that this dyke and that at 
Tokatea can be correlated on their similar lithological characteristics. Since rhyolitic intrusions have 
never been found associated with the andesitic rocks of the " First " or " Second Periods," the 
irruption of these dykes apparently followed close upon the extrusion of the rhyolites, constituting the 
earliest(?) of the " First Period " volcanics. 

Petrology. 

The intrusive rhyolite from Tokatea is a white or greyish-white rock, strewn with quartz grains or 
showing numerous small cavities from which small grains or bipyramids of quartz, cubes of pyrite, and 
other minerals have disappeared. Under the microscopef the groundmass of this rock consists of a 
mosaic of interlocking quartz grains, dusty with sericite, and opaque white granules. In this ground- 
mass grains of quartz, some rounded, others bipyramidal, are scattered like phenocrysts, and contain 
liquid and vapour cavities. Aggregates of muscovite with rectilinear boundaries are clearly pseudo- 
morphs after some other mineral, and the outlines in some cases suggest a feldspar. 

The Umangawha rock is megascopic-ally identical with that just described, except that it contains 
small isolated plates of deep-brown biotite, which mineral is gradually being replaced by quartz. The 
rock is therefore somewhat less altered than that at Tokatea, which lies within a well-known vein-bearing 
area. 

* "Rooks of Cape Colville Peninsula," vol. i, p. 146, No. 2869. | hoc. cit., vol. i, p. 180, No. 69/3208. 



95 



(5.) SUCCESSION OF LAVAS. 

The chemical analyses of the various igneous rocks have, for purposes of comparison, been 
brought together in the following tabulation : — 







First Period. 




Second Period. 


Third 


Intrusive. 














6. 


7. 


Period. 








1. 


2. 


3. 


4. 


5.* 


8. 


9. 


10. 


Silica (Si0 2 ) 


69-30 


57-25 


55-58 


53-28 


48-90 57-68 


60-40 


72-40 


57-32 


57-32 


Alumina (A1 2 3 ) 


13-92 


16 39 


17-27 


17 54 


1767 18-84 


17-84 


1409 


17-69 


16-56 


Ferric oxide (Fe 2 3 ) 


0-48 


0-40 


112 


1-20 


1-20 


4-96 


6-40 


(MS 


2-24 


9-28 


Ferrous oxide (FeO) 




7 35 


7 4 1 


7-92 


706 


1-44 




2-52 


5-62 




Mauganous oxide (MnO) 


i»Il' 


0-36 


040 


0-78 


019 


0-21 


005 


0-42 


0-21 


025 


Lime (CaO) 


217 


1 50 


7-30 


7-70 


1100 


605 


4-30 


115 


6-50 


6-05 


Magnesia (MgO) 


0-25 


3*55 


is:, 


5-26 


3-91 


4-00 


013 


0-20 


3-66 


012 


Potassium-oxide (K 2 0) 


3-79 


1 97 


Dili 


0-26 


0-34 


215 


1-15 


109 


1-25 


1-52 


Sodium-oxide (Na 2 0) 


III 


2-37 


1-50 


2-01 


1-89 


216 


2 16 


2-97 


404 


2-38 


Titanium-oxide (Ti0 2 ) 


018 


0-92 


Oti7 


0-61 


0-98 


0-82 


0-41 


015 


0-85 


0-48 


Carbonic anhydride (C0 2 ) 


2-56 


1-38 


1-45 


1-24 


487 


0-75 


0-30 


0-82 


0-67 


3-20 


Water and organic matter 


2-40 


3-25 


205 


2-08 


2-28 


0-90 


7-00 


0-86 


013 


2-50 




99-72 


9969 


10006 


99-88 


100-29 99-96 


100-44 


100-15 


100-18 


99-66 



* The greater alteration of this rock, as shown by the percentage "f lime and carbonic anhydride contained therein, 
partly accounts for its low percentage of silica. 

1. Rhvolite tuff, from Omoho Creek. (Page 64.) 

2. Hornblende andesite, from Waikoromiko Creek. (Page 73.) 

3. Hvpersthene andesite, from Fonr-in-Hand Mine. (Page 70.) 

4. Augite andesite. from Maiden Mine. (Page 71.) 

5. Andesite, showing free quartz — dacitic(?) — from Whangarahi Creek. 

6. Hvpersthene andesite. from Beeson's Island. (Page 82.) 

7. Andesite(?). from Long Bay. (Page 82.) 

8. Spherulitie rhvolite. from Puiangi. (Page 87.) 

9. Quartz-biotite diorite, from Moehau. (Page 90.) 
10. Hornblende andesite with free quartz (probably " Second Period 

(Coromandel). (Pagei'3.) 



(Page 74.; 



rock), from Trig. Hill 



It seems probable that the whole of the Tertiarv igneous rocks have been derived by a process of 
differentiation from a common magma. 

It is difficult to account for the existence of the rhvolite (1). This rock, which was the first or om- 
of the first extruded in Tertian- times, appears in only one locality, and covers a relatively small area. 
Its extrusion was immediately succeeded by eruptions of andesitic rocks, which continued inter- 
mittently to the close of the " Second Period." 

Certain considerations favour the " assimilation theory " as accounting for this apparently minor 
and isolated extrusion of rhvolite. It seems reasonable to suppose that, if an andesitic magma, in 
" stoping " its way up to the surface, encountered in a certain locality a considerable stratum of rhvolite, 
its first extrusion would afford a lava at least moderately acid, and therefore such as the rock under 
consideration. Immediately to the south of the rhyolitic extrusion under discussion older rhvolites do 
occur as heavy interstratified bands in the Tokatea Hill Series, and such may reasonably be supposed 
to underlie the strata of the Moehau Series upon which the Tertiary rhvolite (1) rests. It is also signi- 
ficant in this connection that the principal rhvolite dyke (Tertiary ? — see page 94) exposed in the basement 
sedimentaries is associated with the old interbedded rhyolites of this same locality. 



96 

Apart from the rhyolite discussed, the Tertiary lavas of the subdivision present on the whole a 
gradually increasing acidity : — 

" First Period," andesites, 48-90 to 57-25 per cent, of silica (Si() 2 ) ; or, excluding No. 5, 53-28 

to 57-25 per cent, of silica (Si0 2 ). 
" Second Period," andesites, 57-68 to 60-40 per cent, of silica (SiU 2 ). 
" Third Period," rhyolites, 72-40 per cent, of silica (Si0 2 ). 
These silica percentages are, however, subject to the alterations which the rocks have undergone. 
In the typical Beeson's Island andesite (" Second Period ") the percentages of potash and soda 
are almost equal, and the rock appears to occixpy an intermediate position between the " First 
Period " andesites, in which soda is in excess, and the " Third Period " rhyolites, in which potash is 
in excess. 

As regards the intrusive rocks, the andesite (10) probably belongs to the " Second Period " of 
vulcanism, and agrees fairly closely with the effusives. 

The quartz diorite (9) (see page 88) may be of Pre-Jurassic age, but has apparently been derived 
from a magma differing little in chemical composition from that which supplied the Tertiary andesites. 



(6.) IGNEOUS ROCKS AS BUILDING-STONES. 

The semi-basic igneous rocks of the area under review afford few stones suitable for building 
purposes. The great majority of the rocks possess a texture and appearance, as well as a lack of rift, 
which renders them altogether unsuitable for architectural work. In addition to these inherent disad- 
vantages, very many of the rocks show considerable alteration due to hydrothermal action. This 
alteration results in very great diminution in the general strength and durability of the rocks, and 
thus renders them useless even for the roughest constructional purposes. 

Diorite. — The rock of greatest commercial value yet located in the area is the quartz-biotite diorite, 
occurring on the western slopes of Moehau Range. This is a greyish granite-like rock showing white 
feldspar, greenish-black biotite, and other ferro-magnesian minerals of even grain. Both the mineral- 
ogical and chemical composition of this diorite have been detailed on page 90. 

The rock possesses rather better rift and general working qualities than are usually associated 
with members of the diorite family. Fairly large blocks have been quarried and dressed for monu- 
mental and decorative purposes, with effects equal to the best grey granite. An average specimen of 
this diorite, on being tested, showed a water-absorption of 0-254 per cent, of its weight, in 150 hours ; 
this result compares f avoui ably with those afforded bv the best granites. 

The steep slopes of Moehau Range, besides being in general covered with a heavy layer of surface 
debris, are, moreover, heavily bushed. This renders it impossible to estimate the extent of the rock in 
question. Further exploitation, however, will probably prove that there exists a considerable amount 
in a condition suitable for quarrying. All of the stone quarried up to the present has come from the 
coast-line some 60 chains north of Darkie Creek, but prospecting operations are said to have revealed 
its existence at a point on the hillside further south. The quartz diorite is exposed in many of the creek 
beds in this vicinity, and therefore the discovery of outcrops of the rock is not a difficult matter. The 
location, however, of the rock in a fresh condition is not so easy, for considerable areas have been 
affected by hydrothermal action. Pyrite is a common secondary mineral, and its oxidation -products 
give rise to rusty stainings, which render even the hard rock unsuitable for decorative purposes. 

Should further exploitation at the quarries prove that considerable amount of stone exists, the motive 
power of some of the adjacent high-grade creeks might be made available for operating stone-cutting 
saws. A block of stone submitted to a sawing test exhibited surfaces showing little or no pluck structure, 
and it seems certain that the installation of sawing machinery on the quarry property would effect- a 
saving in the cost of production. 



97 

Pumiceous Tuffs and Breccias. — Rocks of quite a different character to that just described, and 
having a commercial value as building-stones, are some of the pumiceous tuffs and breccias occurring 
in the vicinity of Mercury Bay. 

The particular type of these rocks which possesses the greatest strength and durability is the 
pinkish-grey compact tuff or fine-grained breccia forming the headland extending north from the Ferry 
Pier and bordering the eastern side of Whitianga Harbour (see page 86). The rock is favourably jointed 
for quarrying, and is in a splendid position for shipment and transportation to the Auckland market. 

Large cuboidal blocks of the rock were employed in the construction of the Ferry Pier and in the 
foundations of the old sawmill on the east side of Whitianga Harbour. The stone in these structures, 
after some twenty-five years' exposure to the weather, is still in an excellent state of preservation, the 
tool-marks, as McKay* notes, " being yet almost as keen as when the rock was first cut into or 
dressed." A test showed that this tuff absorbed water to the extent of 15-600 per cent, in 150 hours. 
A somewhat similar rock to that found in the vicinity of the Ferry Pier forms the hills in the vicinity 
of Trigonometrical Station V, on the western side of the harbour. A very small expenditure might 
show that a considerable amount of marketable stone exists in this locality. 

A white pumiceous fine-grained tuff, closely resembling the Oaniaru limestone, but rather softer, 
forms Whitianga Rock and other conspicuous cliffs on the eastern side of the harbour. This rock, which 
splits and saws easily, and is often remarkably free from joints, might be found applicable for special 
purposes. It has alreadv a reputation for withstanding satisfactorily the action of a moderate heat, 
and in this connection has been used for the linings of bakers' ovens, and other similar structures. 
Reference has already been made (page 85) to the propertv this rock possesses of forming a hard 
white siliceous skin on surfaces exposed to the weather. 

The occurrence of massive rhyolite, consisting almost entirely of spherulites, has been noted. The 
fresh specimen of this rock indicates that it would take a good polish, and might serve for an ornamental 
stone. More than a surface examination, however, is necessary to determine whether a considerable 
amount of undecomposed rock of this class exists in an accessible locality. Some of the hills in the 
vicinity of Purangi Estuary present possibilities in this connection. 

Bock for Road-making. In many localities the igneous rocks possess considerable value as furnishing 
a plentiful supply of rock for road-making purposi 

♦('. '.i. lstiT. p. 69. 



7 — L'oromandel. 



98 



CHAPTER IX. 



MINERAL VEINS. 



Introduction 
Periods of Mineralisation 
The Circulation Channels or Vein Fissures . . 
The Mineralising Agents 
Rock-alteration connected with Mineralisa- 
tion 
Mineralogy of the Ore and Gangue Minerals 



Page 
98 
98 
99 

100 

100 
101 



Structure of the Vein-material 

Oxidation 

The Ore-shoots. . 

The Origin of the Gold and Silver 

Distribution of the Veins 

Detailed Description of Special Areas 



Page 
105 
105 
106 
107 
107 
108 



Introduction. 

The Coromandel subdivision of Hauraki owes its importance as a mining-area exclusively to the 
occurrence of gold-silver veins. Complex sulphide ores, in which lead and copper form the valuable 
metalliferous content, have been mined in a desultory manner from certain claims in Petote Creek, but 
the total value of the few tons of this ore exported is economically insignificant. This is the only 
instance, in the subdivision, of ores having been exploited for metals other than gold and silver. 

The veins occur in the sedimentary complex forming the basement or floor of the area, and 
in the Tertiary volcanics of the " First " and " Second Periods " which overlie these sedimentaries. 
There is evidence to show, however, that the veins associated with the basement sedimentaries are 
genetically related to, and dependent upon, the Tertiary andesitic eruptives. The veins vary in dimen- 
sions from mere thread-like partings to strong well-defined " reefs " exceeding 60 ft. in width. The 
experience of the past has shown, however, that, as far as mining operations have been extended, the 
larger occurrences are not payably auriferous. The field has been noted for its ore-shoots of the bon- 
anza type, the rich vein-material designate d in local mining terminology " specimen stone," and valued 
at " ounces to the pound," having contributed far more to the total gold-output than ore valued at 
" ounces to the ton." As is the general rule in veins of this type, faults, cross-courses, cross-veins, and 
mineralised bands, as well as the character of the wall-rock, have all exercised an important influence 
on the position and value of the ore-shoots. Much of the information respecting the characteristics 
of the veins and their environments must unavoidably be expressed in rather general terms in the 
present bulletin. The examination of underground conditions was precluded by the temporary cessa- 
tion of pumping operations in the case of all those mines working below the ground-water level, and 
by the discontinuance of mining operations in the cas. of most of those mines which may be styled 
" water-free." 



Periods of Mineralisation. 

The metalliferous veins of the Coromandel subdivision appear to be referable to at least two 
distinct periods of mineralisation. The earlier veins are in the main associated with the Tertiary 
volcanic rocks of the " First Period," but are also found in the Jurassic and Pre-Jurassic sedimentaries. 
These veins occurring in the mining-areas of Coromandel Township, Waikoromiko, and elsewhere do 
not extend into the younger andesites (Beeson's Island Series), which in these localities flank the older 
volcanics ; hence they were evidently formed before the eruption of the younger andesites. 
fjSflf. To this period of mineralisation may be ascribed the veins of all the mining-areas lying to the 
west of the main mountain divide ; those of the Tokatea Hill, Success Hill (Kaipawa), and other 
localities on the main divide ; and those occurring within the belt of " First Period " volcanics, extending 
from Matamataharakeke to the Upper Mahakirau Valley on the eastern side of the mountain divide. 

W, Veins formed during the second period of mineralisation are apparently confined to certain areas 
on the eastern side of the main range. They occur in the andesites of the Beeson's Island Series at 






r^ 







d 

<3 



99 

Materangi. .Murphy's Hill, Owera. and Moewai, all situated on the inner portion of the Kuaotunu 
Peninsula, and in the basement sedimentaries at the main Kuaotunu mining centre. With these should 
possibly be correlated the " Silver Lode " of Tangiaro Creek, Port Charles, occurring near the contact 
of the " First" and " Second Period " volcanies. The veins of both the first and second periods of 
mineralisation, whether occurring in the basement sedimentaries or in the neighbouring volcanies, are 
due to similar causes. It is evident that they were formed by the ascent of heated mineral-bearing 
waters during the solfataric periods succeeding and connected with the extrusions of the volcanies. 
Since the andesites of the " First Period " were the results of several eruptions separated in certain 
cases bv relatively long intervals of quiescence, the time-range of the earlier period of mineralisation 
was probably considerable, and therefore the veins may not all be contemporaneous. This appears 
to be exemplified in the Kapanga Mine, Coromandel (see page 66), where the andesitic tuffs of the upper 
and lower mine-levels are separated by an old land-surface, and each of the two horizons is said to be 
intersected by independent veins. 

A few quartz veins occur in the dyke-intruded sedimentary rocks of the Moehau Range, but have 
yielded no ore of commercial value. The age of these occurrences is as uncertain as that of the intru- 
sives, and need not be further considered. 

Thk Circulation Channels or Vein Fissures. 

The openings which afforded the channels for the circulation of the mineralising solutions, and 
formed the depositaries of the vein-materials, were in the main fairly well-defined fissures, but not 
infrequently sheeted zones or complex fractures of rather poor definition. The cause of this fissuring 
is not far to seek in a region which exhibits sedimentary rocks largely intruded by dykes, and overlain 
by volcanic rocks extruded at various time-intervals. Some of the vein-fissures, and most Likely those 
of greater persistence, are due to faulting ; but the amount of movement is difficult to determine in the 
case of the altered volcanic rocks, owing to the absence of points on the opposite sides of the fracture- 
plane, which can be correlated. In addition to the evidence afforded by striated slickensides and 
selvages, faulting in the vein fissures can be infernal from its frequency in the case of the post-mineral 
Fractures, where displacements of 30 ft. to 40 ft. are in places observable. In the stratified rocks of the 
Royal Oak Mine (Tokatea) displacements of strata to the extent of a few feet were observed by the 
writers, even in connection with some uf the minor veins. 

In addition to fissures of faulting, others, it would appear, were due to the contraction of the 
eruptive material, or to minor Btreasea caused by the still-existing volcanic energy. These openings 
can have little or no extension into the underlying basement sedimentaries ; hence the veins formed 
in them are likely to " give out '" in depth. 

Within the mining centres fissures are exceedingly numerous, the dominant ones in any particular 
locality showing a general parallelism ; the minor ones being disposed parallel to the larger or junction- 
ing with them at various angles. The map (page 110) of the veins and faults of the Hauraki group 
of mines shows the complexity of the rock-fracturing in an area which has been characterized bv great 
mineralisation. Generally speaking, the vein fissures of the Coromandel subdivision show a preference 
for strikes approaching the meridional rather than the latitudinal direction. Since the general strike 
of the basement nicks also approaches north and south there may be inure than a casual connection. 

It is difficult to speculate as to the age of the fissuring in any locality. Some of the vein fissures 
intersecting breccias ne such sharp well-defined breaks that it would seem impossible that they could 
have been formed prior to the consolidation and considerable alteration of the rock. The vein fissures 
in the Pre-Jurassic rocks oi the Royal Oak Mine were cc-rtainlv formed after the intrusion of the porphv- 
rite dykes, but, whereas the veins are certainly Tertiary, these particular dvkes may be of considerably 
greater antiquity. 

The fissures naturally vary in character according to the nature of the rocks they intersect. The 
principal veins of the Hauraki group of mines, intersecting, in the main, altered massive andesites, are 

sharply demarcated from the wall-rock. These veins often present a somewhat lenticular form, 
due apparently to fault-movement along slightly sinuous fractures. Small " horses " and angular frag- 
7* — Coromandel. 



100 

incuts of country rock broken from the walls and cemented in the vein-material are not uncommon 
features. In the less-altered massive andesites of the Coromandel mines, and the similar phases of 
the grits and argillitcs of the Kuaotunu mines, the fissures show considerable contraction in width, and 
are, to use the miners' expression, " pinched." 

The hard porphyrite dyke of the Royal Oak Mine, which is intersected by the " Tribute leader." 
shows conditions of fracture analogous to the comparatively impervious and unaltered andeaite. The 
vein on its course through the dyke is either a single band of greatly reduced width, or is represented 
only by a few small stringers. The fissures in the breccias, as already intimated, appear to be regular 
and well defined, or erratic and poorly defined, according as to whether they were formed before or 
after the consolidation and considerable alteration of these rocks. 

The Mineralising Agents. 

The mineralising agents which circulated in these fissures were evidently aqueous solutions, as 
judged from the character of the vein-material and the nature of the alteration of the wall-rocks. That 
these solutions were hot, and in the main ascending, there is also little reason to doubt ; they were 
evidently active during the periods of solfatarism which marked the closing phases of certain manifes- 
tations of vulcanism. 

As to whether these waters were of meteoric or magmatic origin is at the present time one of the 
debatable questions of ore-genesis. It may be here remarked that a detailed survey of the Rotorua 
hydrothermal region immediately to the south of the Hauraki Division, should throw some light on 
this subject. The fact has, however, already been noted* that hot-spring and geyser action at Rotorua 
has more than a fortuitous dependence on the rainfall and general hydrostatic conditions. 

Rock-alteration connected with Mineralisation. 

In all mining-fields in which mineral veins are associated with andesites, an alteration of these 
rocks to a propylitic or similar facies is a characteristic phenomenon. The andesites and dacites of the 
vein-bearing areas of the Coromandel subdivision offer no exception to the general rule, and have been 
profoundly altered by an active circulation of thermal waters. The nature of the alteration which these 
rocks have undergone, although not agreeing exactly with the propylitic facies determined by Rosen- 
busch, has for convenience' sake been termed " propylitic " in a previous chapter. (See page 74.) 

The conditions of mining existing in the Coromandel area during the years 1906-7 did not admit of 
the investigation of the various transitions and phases of rock-alteration which undoubtedly exist. 

The most extensive vertical section through altered andesites in a vein-bearing locality is that 
afforded by the Kapanga shaft (1,000 ft.) and the borehole sunk from the bottom of this shaft for a 
further depth of 225 ft. It is stated that a pronounced alteration of the andesitie rocks to a bluish- 
white pyritised kaolinic-like mass obtained for a depth of some 400 ft. from the surface. Silicification 
is not an uncommon feature of this alteration, and many of the blebs of quartz that have sometimes been 
regarded as the remnants of the primary quartz of a dacitic type of andesite, are probably secondary 
products. This upper 400 ft. has proved essentially the zone of the rich bonanza ores. From the 400 ft. 
to the 900 ft. level the andesites penetrated were harder, and of a dark-greenish colour ; alteration in 
this zone apparently resulting mainly in the development of chlorite and, in a lesser degree, of car- 
bonates. The veins which in the highly propylitic rock of the upper zone were rich in the precious 
metals were here found to be contracted in width, and either barren or of very low grade. Below 
the 900 ft. level exists another zone of propylitic andesites, which continues to and beyond the 
greatest depth exploited (1,225 ft.). The limited amount of development-work done at the 940 ft. 
level yielded pockets of bonanza ore, smaller in extent but comparable in richness with those occurring 
nearer the surface. 

In the Hauraki group of mines analogous conditions obtain, but the barren zone of chlorite-car- 
bonate(?) alteration, which underlies the highly propylitic productive zone, has not been completely 

* J. Malcolm Maclaren : Geological Magazine, vol. xiii, 1906, p. 511. 



101 

penetrated. It is stated, however, by mining-men formerly connected with the Hauraki Mine that 
excavating in the shaft, to provide for a "sump" below the deepest mine-level (400ft.), revealed a 
gradual change from the hard dark-greenish rock to a phase simulating that of the productive upper 
zone. 

The reasons for this zonal arrangement or stratification of the country rock showing the different 
phases of alteration are, in the absence of accurate data, not very evident. The old land-surface (coaly 
seam) encountered in the vicinity of the 940 ft. level in the Kapanga Mine might suggest a period of 
solfatarism with attendant rock-alteration and vein-formation in this locality prior to the accumulation 
of the overlying andesites. This would account for the highly propylitic rock of the lower levels of 
this mine underlying the darker-coloured, less-altered rock. There is no evidence, however, to suggest 
that similar conditions can be held to account for the alternating zones which are considered to exist 
in the Hauraki Mine. Whether such zones are due to alternations of rock of greater and lesser per- 
meability, or are capable of some other explanation, must for the present remain an open question. The 
solution of the problem has a decided economic bearing, as these are essentially the productive and 
non-productive zones of this goldfield. 

The acidic tuffs and tufaceous mudstones Lnterstratified with the Pre-Jurassic argillites and grau- 
wackes (Tokatoa Hill Series) are the rocks enclosing the auriferous veins of the Royal Oak and other 
mines of the Tokatea Hill. These pyroclastic volcanics and the sedimentaries have been altered by the 
n mi ■ agencieB which have effected the propyhtisation of the andesites. The rocks have assumed a light 
colour and have heen considerably silicified and impregnated with pvrite, but as their original character 
is obscure it is Impossible to more precisely determine the nature of the alteration. 

The grits and argillites of the Manaia Hill Series (Jurassic) are the rocks associated with the auri- 
ferous veins of the Kuaotunu mining centre, (twine to the great amount of andesitic and rhvolitic 
detritus which enters into the composition of the rocks, the altered product closely resembles tin' pro- 
pylitic andesites. The highly altered and productive zone of the upper mine-levels at Kuaotunu gave 
■r depths to a much less altered phase of the same rocks, this change being attended with a 
contraction in width and an impoverishment in value ol lie veins. 

The rock-alteration already described in somewhat general terms is that attendant upon change 
of level. If, however, the vein fissures are regarded as the focal planes from which thermal waters and 
vapours were diffused throughout the wall-rock, lateral transitions from highly altered to comparatively 
unaltered rock might be expected. Mining operations have disclosed such lateral transitions. The 
country rock separating two veins approximately parallel with each other has, in certain instances, 
been found to grade laterally from the vein-wall, where it assumes a highly propylitic facies, to a median 
rib of dark and only slightly altered jrock. These ribs or dyke-like masses are the " hard bars " 
of the miners. In some cases, however, these " hard bars " are probably due to dykes (see page 111). 
Such a uniform lateral transition as that described is, however, the exception rather than the rule. 
In the Four-in Hand Mine large spheroids of hard, dark rock, showing only a minor amount of alteration, 
are encountered in and near the actual vein fissure ; again, in the same mine dark and only slightly 
altered massive andesite in places forms the rock on the hanging-wall side of the vein, while rock 
primarily the same, but now light-coloured and highly altered, constitutes the rock extending for a 
considerable distance from the foot-wall. 

In addition to rock-alteration proceeding from vein fissures, other areas of highly altered andesite, 
in which no veins have been detected, would appear to be explainable oidy as the result of a general 
rise of thermal waters through the main mass of the rock. .More especially is this likely to have occurred 
where the volcanic accumulations were at the time of solfataric action of a readily permeable character. 

Mineralogy ok the Ore and Ganque Minerals. 

The veins of the Coromandei subdivision can hardly be said to a.tford a great variety of minerals, 
although a list covering all the occurrences that have from time to time been identified is somewhat 
lengthy. 



102 

Quartz, and to a lesser extent pyrite, invariably constitute the main gangue-minerals of the gold- 
silver veins. Calcite is not an infrequent vein-constituent, and occasionally equals in bulk the quartz 
with which it is associated. Galena, chalcopyrite, and the alteration-products of the latter mineral 
become abundant in certain lenses of the veins, near or at the contact of igneous and sedimentary rocks. 
A low gold-content, however, appears to characterize all these galena-chalcopyritel ores. Stibnite 
to an amount of 13*5 per cent, of the ore occurs in some of the unexploited veins of the Mahakiran 
district. The prominence attained by the various other minerals will be gauged approximately from 
the descriptions which follow. 

The minerals detected from time to time during the course of # mining operations have been the 
subject of notices by previous investigators, and on these notices the writers of the present bulletin 
have largely drawn. 

Non-metallic Minerals. 
Quartz. — Quartz is the chief gangue-mineral in all the veins, both as fissure-filling and to a lesser 
extent as the result of silicification of the wall-rocks. It is generally finely crystalline, or, again, is 
crystallized in small prisms terminated by pyramidal faces, the colour in either case being white or 
bluish white. Transparent quartz crystals of considerable beauty often occur in the veins at Opitonui 
and Tokatea on the walls of some of the larger geodes or vugs. Much of the quartz of the Kuao- 
tunu area is milk-white, and exhibits the platy or laminated structure usually attributed to pseudo- 
morphism after calcite. Rhombohedral cells, fined internally with fine drusy quartz, are fairly common, 
and are evidently due to the replacement of portions of the original calcite, and the removal of the 
remainder by solution. In other portions of these veins in which the platy quartz occurs, cellular, 
saccharoidal (" sugary "), and occasionally banded quartz are found. 

Amorphous and Cryptocrystalline Silica. — Chalcedony, carnelian, and jasper are common in minor 
fissures in the argillites, and occasionally in the volcanic rocks. Siliceous sinter forms veins in the 
rhyolites of Purangi and in certain areas of the Beeson's Island tuffs. It has also great develop- 
ment as terraces and pipes in the Waitaia Ridge, Kuaotunu, and elsewhere. 

Calcite. — Calcite occurs as rhombohedra, scalenohedra, hexagonal prisms, and various modifica- 
tions of these forms. It is in colour generally milky-white, sometimes colourless, and occasionally 
yellow ; the latter coloration is due probably to iron-oxide. 

As regards the occurrence of this mineral, Maclaren remarks, " Iceland spar is common in the 
Tokatea Mines, perfect crystals up jto half an inch being obtainable. In the colourless varieties, 
however, the cleavage-planes are so visibly abundant as to render the crystals valueless for Nicol's 
prisms, &c. . . . Dogtooth and nailhead spar in scalenohedra are common in Scotty's Reef 
in the Kapanga area. Argentine, a pearly lamellar calcite, is found in the Tribute Reef, Tokatea." * 

Aragonite. — Aragonite is found in stellate needles in Scotty's Reef (Kapanga). 

Mirabilite, <n- Glauber's Salts. — The hydrous sulphate of soda (Glauber's salts) occurs in minute 
quantities in old drives and workings. 

Epsomite. — Epsomite, the hydrous sulphate of magnesium, occurs as an efflorescence in the form 
of long rhombic silky prisms, on the walls and roofs of old drives and workings. It is referable to the 
alteration of wall-rock rather than of vein-material. 

Kaolin. — An undetermined kaoiinic product — the "pug" of the miners — is fairly abundant in 
the reefs. In part it probably results from the decomposition of the feldspathic constituents of the 
wall-rocks, and in part from an extremely fine comminution of the wall-rocks along planes of move- 
ment. 

Metallic Minerals. 

Gold. — The gold of all the veins in the area under review occurs in association with silver as an 
plectrum. The proportion of gold to silver in the bullion derived from the average ores by the amalga- 
mation process varies from 1 : 075 to 1 : 0-30. The greater percentage of silver present in the bullion 



* CL-9, 1900, p. 16. 



103 

obtained from the same ores by a solvent (cyanide) process or by fire assay indicates that not all of this 
metal is alloyed with the gold. In the great majority of the payable ores the electrum occurs as a dis- 
semination of coarse metallic particles or filaments, and less frequently of particles in such a finely divided 
state as to be almost invisible to the unaided eye. Visibly crystallized gold (electrum) has been 
frequently detected in the Tokatea area : but the crystals are generally very imperfect, showing as a 
rule only a single edge or face. A rather perfect specimen, however, known locally as " the golden 
butterfly " was discovered sonic years ago in the Rainbow Reef, Tokatea, and has been described by 
Maclaren. The specimen, this writer remarks, "is probablv unique in possessing a form composed of 
the cube, octahedron, and rhombic dodecahedron."* 

Silver. — The occurrence of silver as associated with gold lias already been described. Argenti- 
ferous galena also occurs, but in small quantities. 

Argentite (Silver-glance). — Argentite as bluish-black bands is the principal ore-mineral of the 

" Silver Lode," Tangiaro Creek, Port Charles, and occurs sparingly in some of the quartz veins of the 

Matawai Valley, Waiau. The mineral apparently occurs in the massive form ; no crystal-outlines 
have been identified. 

Pyrargyrite (Ruby-silver). — The occurrence of small cochineal-red crystals of pyrargyrite in a 
vein of the Golden Pah Mine. Commanded, is reported by Maclaren. 

Kerargyrite (Horn-silver). — Several pounds' weight of the chloride of silver, kerargyrite. are reported 
to have been obtained some years ago from the Waikorbmiko Valley. 

Cinnabar (Sulphide of mercury). — The presence of cinnabar is reported by .1. A. Pond from various 
parts of the Hauraki Peninsula CoromandeL among others — " but in no instance is it present in large 

or well-defined quantities. "f No indication is given as to the actual locality of the specimen. 

1'ijritP (l)isulphide of iron). — Pyrite is. next to quartz, the mineral of most widespread occurrence 
in the veins of this goldfield. It OCCUI8 as cubes and pyritohedrons, and in tin' massive state. 

Marcasite (White iron-pyrites).- Slarcaaite has been found associated with pyrite in the veins 
of the Matawai Valley and elsewhere. 

Mispickd (Arsenopyrite — Sulphide and arsenide of iron). — Mispickel occurs in association with 
pyrite and stibnite in the veins of the Matawai, Mdiakirau. and Cinangawha Valleys, and the garlic 
odour which this mineral emits when struck with steel is frequently observed in the mines of the 
Kapanga and Hauraki groups. 

Melanterite, or Copperas (Sulphate of iron). Melanterite, as an oxidation-product of pyrite, has 
been observed forming small stalactite* in the mines of the Hauraki and Kapanga groups. 

llmenite (Oxide of iron and titanium). — The occurrence of massive ihnenite as rolled pebbles in 
the Waikoromiko Creek has been reported. J 

Ihi nmtite (Oxide of iron). — Ha-matite forms pseudomorphs after calcite in the Trv Fluke vein, 
Kuaotunu. Earthy forms of this mineral in association with limonite are of general occurrence. 

Limonite (Hydrous oxide of iron). — Hydrous oxides of iron are common, as oxidation-products of 
pyrite, in the gossanous weathered portions of the veins. 

Native Copper. — Native copper has been found as small grains associated with the chalcopyrite 
in the veins of Petote Creek (Coromandel). also very sparingly in some of the ore of the mines of the 
Kapanga and Hauraki groups. 

Chalcopyrite (Copper Pyrites— Sulphide of copper and iron). — Cha copyrite is fairly abundant 
in senile of the veins, especially those occurring in or near the basement sedimentaries. 

Bornite, or ErvbescUe (Sulphide of oopper and iron). — Bornite is found forming an iridescent film 
on chalcopyrite in the veins of Petote Creek and elsewhere. 



• C.-9, 1900, p. 16. +C.-3, 1887, )>. 58. ' 9, 1900, |». IT. 



104 

Malachite (the Green carbonate of copper). — Malachite is found as an alteration-product wherever 
chalcopyrite occurs. 

Azurite (the Blue carbonate of copper). — Azurite occurs under the same conditions as malachite. 
Tetrahedrite (Sulphide of copper and antimony, with silver, &c.). — Tetrahedrite is reported to have 
been identified from a vein occurring in Koputauaki Bay. 

Galena (Sulphide of lead). — Galena is of fairly common occurrence in the veins occurring in or 
near the basement sedimentary rocks. It is argentiferous, but not highly so. 

Hedyphane (a variety of Mimetite — -Lead arsenate and chlorate). — The occurrence of mimetite, 
in which the greater part of the lead is replaced by calcium, is reported by Maclaren from certain clayey 
partings in the basement sediment aries. 

Sphalerite, or Zinc Blende (Sulphide of zinc). — Sphalerite occurs in association with galena and 
chalcopyrite in the veins of Petote and Tiki creeks. 

Nickel. — Cox * refers to a " foliated serpentine " from Coromandel having yielded a trace of nickel. 

Native Arsenic. — Native arsenic occurs in several of the mines on the Tokatea-Kapanga-Hauraki 
auriferous belt. In the West Tokatea and other mines situated just to the south of Tokatea Saddle, 
the arsenic Usually takes the form of reniform nodules. The mineral on exposed surfaces is of dull- 
black colour, but on fresh fractures exhibits its characteristic greyish-white metallic lustre. Geodes 
exceeding 6 in. in diameter are not uncommon, and often enclose filaments of gold. In the Kapanga 
Reef arsenic as reniform nodules and in massive forms has been observed, while in the Hauraki North 
reefs the mineral generally occurs massive. 

Arsenolite (As 2 3 ), Orpiment (As 2 S 3 ), Realgar (AsS). — The oxide and sulphides of arsenic were 
noted by Maclaren from Tokatea Hill "as an incrustation on the exposed wall of a reef." f 
Arsenopyrite.—See Mispickel (page 103). 

Antimonite, or Stibnite (Sulphide of antimony). — Stibnite occurs granular, or as rhombic prisms 
arranged in spine-like or stellate form, in several veins of the upper Mahakirau Valley. Analysis of 
some of the vein-material has shown the presence of an amount of stibnite equivalent to 9 '66 per cent, 
of antimony. The mineral also occurs in the veins of the Matawai Valley, and to a lesser extent in the 
veins of the Hauraki Freehold and Blagrove's Freehold Mines. 

Kermesite (Sb 2 S 3 + Sb 2 3 ). — Kermesite, according to Maclaren, occurs in cherry-red fibrous 
crystals as an incrustation on the reef in the Hauraki North Mine (now Hauraki Freehold).! 

Native Bismuth. — A fragment of native bismuth discovered in the gravels of Wade Creek (Mahaki- 
rau) a few years ago led to a certain amount of prospecting for this mineral. The source of the detrital 
fragment was, however, not located. 

Tellurium. — Apparently the only reference to the occurrence of tellurium within the subdivision 
appears to be in a paper by F. B. Allen, formerly Director of the Thames School of Mines. The notice 
is as follows : " Tellurium has been found by the author? (among other places) at Coromandel. . . . 
Quartz containing 25 per cent, mispickel : Assay — 200 oz. gold per ton, 90 oz. silver per ton. 1 *! This 
ore contained a little tellurium, the amount of which was not estimated. A considerable quantity of 
the ore was roasted without loss of bullion."! The writers of the present report have not been able to 
ascertain the actual locality from whence this quartz was derived. 

Pyrolusite and Wad. — The black oxides of manganese, pyrolusite and wad, occur frequently 
though never in great quantity in the veins of the subdivision. These minerals, imparting a black 
stain to the vein-quartz, are characteristic of Tokatea Hill, Kuaotunu, and Materangi. 

Rhodonite and Rhodochrosite. — The presence of rhodonite and rhodochrosite, the silicate and 
carbonate of manganese, is indicated by the amethystine coloration which the quartz and calcite of 
the veins occasionally present. 

* IVans., voL xiv, 1881, p. 43ti. t C-9, 1900, p. 17. % Sew Zealand Mines Record, vol. iv, 1901, p. 409. 



To accompany Bulletin IP.9 4-. 




105 

Structure of the Vein-material. 

The larger structures of the veins, being dependent upon the character of the fissures, will be 
inferred from a previous section (page 99). Only the arrangement of the various minerals -within the 
fissures need be here described. 

The majoritv of the Coromandel veins, and especially those of economic importance, range from 
2 in. to 10 in. in width and are in general characterized by a very vuggy structure, although compact 
vein-filling often occurs. 

The mineral material deposited from the circulating solutions first formed crusts on the fissure- 
walls. These crusts, which themselves contain numerous small vugs, gradually grew outwards from the 
walls in rather irregular fashion, sometimes uniting to form a solid sheet or again leaving open spaces 
or larger vugs between them. These larger vugs, while often arranged along the medial planes, may 
again, on account of irregular crust-growth, be found to show no definite arrangement in the vein. Like 
the smaller ones they almost invariably show drusy linings. 

Although these vugs are in the main small, they occasionally attain large dimensions. In the 
Tokatca and Tribute veins of the Royal Oak .Mine, these cavities sometimes exceeded 10 ft. in length 
and a foot in width, and are often lined with very beautiful incrustations of quartz and calcite. The less 
coarsely crystalline quartz forming the main mass of the vein-material between these large vugs and 
the wall-rock was. in certain cases, very highly auriferous. In the much larger vein of the Maiden 
Mine, Opitonui. some great vugs lined throughout with perfectly formed projecting quartz crystals 
were encountered. 

Vein-material showing well-defined banded or ribbon structure is scarcely ever found in the veins 
of the Coromandel centre, although it has been occasionally observed in those of the Kuaotunu field. 
An indistinct banding, rendered evident only by the higher percentage of pyrite ill certain parts of the 
vein-stone than in others, is noticeable in some portions of the more compact material. This feature 

the more evident when the darker pyritic bands were highly impregnated with gold, as in Legge's 
Reef in the Hauraki Mine. 

The Tokatea Big Reef consists in the main of crystalline quartz containing small drusy cavities, 
and in places shows sheeted structure. The foot wall of the vein is sharply demarcated from the wall- 
rock, but the hanging-wall is poorly defined, metasomatio replacement of the andesites being apparent. 
In the Try Fluke veins, Kuaotunu, hollow rhombohedral cavities and platy or laminated structures 
due to replacement after calcite, characterize the greater bulk of the quartz. Saccharoidal or 
" sugary " quartz may be due in part to crushing by rock-movement of the friable vein-material, in part 
to a leaching-out of calcite originally deposited in intimate association with the quartz. 

Minor structures of the vein-material will be noticed in connection with the detailed description of 
individual veins. 

< t.XlliATION. 

At and in the vicinity of the vein-outcrops the ore, owing to oxidation ol the pyrite and iron' 
bearing minei e rally assumes a rusty-brown colour and gossanous appearance. The depth 

to which this oxidation along the veins extends is very irregular, but usually exceeds that of the general 
oxidation of the country rock. The ground-water level of the area cannot now be ascertained, owing 

to the existence "I the numerous old adits which effect the drainage of tin mining claims. It is certain, 
however, that the genera] level of rock-oxidation did not correspond witli that of the ground-water. 
Adits are being driven at the present tune in highly pyritised rock showing no sign of oxidation, and 
these are at levels considerably above that of the original ground-water. Again, country rock stained 
throughout with limonite has been encountered at a considerable depth below the water-level. The 
physical characters of the rocks, and the presence or absence ol fissures, appear to be the main factors 

Tiring the vertical extent of the oxidation-zone. 

In the vein- outcrops, as the result of the usual oxidation processes and removal of soluble salts, 
the following minerals are by far the most abundant : quartz, limonite, manganese-dioxide, and brown- 



106 

stained kaolinic material. With these occur the gold and silver as an electrum, the ratios of the two 
metals differing little from that obtaining in the deeper portions of the veins. In the ehalcopvrite- 
beaiing veins the carbonates malachite and azurite are the usual minerals of the zone of oxidation. 

Thk Ore-shoots. 

The payable ores in the auriferous veins are disposed as shoots or patches — tabular masses of more 
or less definite outline. If the necessary data were available, the mapping of the veins of the various 
notable ore-shoots discovered in this mining-area would be interesting and instructive, but no oppor- 
tunity was afforded of studying these occurrences. 

The pitch-length of these shoots generally exceeds their breadth. The largest of the Hauraki 
Mine bonanzas extended from the surface to a depth of about 260 ft., measured from 120 ft. to 150 ft. 
in breadth, and about 8 in. in average thickness. This shoot had a pitch at high angles to the north- 
ward. The ore-shoots of all the approximately parallel Hauraki veins occurred in corresponding 
positions in the veins, and pitched in the same direction as the main shoot. This is the structure 
termed in the older mining phraseology " ore to ore," or shoots " back to back." In the Iona No. 2 
vein of the same mine the shoot occupied a nearly horizontal position, and occurred at about 60 ft. 
below the original water-level. Where the vein was small (5 in. to 6 in. wide) the bonanza ore formed 
the whole of the vein-stone ; where the vein increased in width to 3 ft. or 4 ft. this rich ore often formed 
about 6 in. on the hanging-wall side, the remainder being of very much lower grade. 

The factors which have exerted the greatest influence on the position of the ore-shoots are (a) 
intersections — namely, " flatheads," carbonaceous seams, faults, cross-courses, dykes, ; (b) the nature 
of the country rock ; (c) depth. 

The effect of intersections on the value of the ores, particularly the rich bonanza ores, is a well- 
established fact on this field. At the intersections of cross-veins, flinties, and " flatheads," the mingling 
of waters that have come from different sources, or, travelling via different directions, have acquired 
different characters, has resulted in precipitation of the gold and its associated minerals. The precipi- 
tation in the vicinity of the carbonaceous seams, of pyrite, and with it gold and silver, owing to the 
powerful reducing action of carbon, is evidenced in the Kapanga and other mines. Further reference 
to this action will be found later (page 117). Faults and cross-courses may have influenced precipi- 
tation in the vein-channels by the supply of precipitating-solutions, but in many cases appear to have 
determined separate systems of circulating ground- waters. In the majority of cases which have come 
under the notice of the writers, the rich bonanza ore occurred in the veins on the upper or hanging-wall 
side of the fault. This would appear to indicate that, locally, at any rate, the waters were descending. 
In certain cases in the Hauraki Mine the ore-shoot terminated on the hanging-wall side of a fault, 
and yet fragments of rich bonanza ore were found in the fault-fissure between the two displaced ends 
of the vein. This would appear to be explainable only by assuming that the gold was deposited subse- 
quent to the formation of the fault, and that a later movement along the fault-plane had dragged in 
portions of the bonanza ore previously formed. 

In the Royal Oak Mine the fact that a porphyrite dyke of greater age than the veins limited the 
ore-shoot will be mentioned in connection with the detailed description of this mine. 

The influence of the country rock on the ore-shoots has already been described to some extent in 
connection with rock-alteration. In certain cases rock-alteration is evidently an accompaniment 
rather than a cause of the deposition of heavily mineralised ore. There are evidences, however, that a 
general rock-alteration and mineralisation sometimes preceded the formation of even the vein fissures, 
and in such cases this altered country rock would have its effect on subsequent ore-deposition. It 
would seem that the physical character of the original rock has been perhaps more important in this 
connection than its chemical character. 

Considering that all the important ore-shoots discovered in this area have been mined from within 
800 ft. and mostly within 400 ft. of the present land-surface, irrespective of its topography, the factor 
of depth is of paramount importance. Viewing the facts broadly, the theory of secondary enrichment 
by the generally accepted processes of dissolution, migration, and redeposition of the metalliferous 



107 

contents of the veins attendant upon a gradual denudation of the land-surface seems the most plausible 
hypothesis. If the extent to which denudation has taken place since the veins were formed could be 
gauged even roughly, the question would be greatly simplified ; but no such estimation seems possible. 
From lack of opportunity, the writers cannot claim to have made a study of the paragenesis of the 
ores. It may be stated, however, that neither the mode of occurrence nor the character of the rich 
bonanza vein-stone is comparable with that of the highly enriched ore occurring in districts where 
" sulphide enrichment " by descending waters is known to have taken place. There are no perceptible 
transitions from the bonanza ores to lean sulphide ores. Furthermore, in the deeper horizons of the 
shoots the ores are generally equal in richness to those of the outcrops and upper levels ; these shunts 
when followed down on their pitch frequently give out suddenly, and are replaced by vein-material 
similar in general character, but containing practically no trace of gold or si!\er. Ore-shoots of 
lesser extent have in places been found to succeed in depth the larger shoots of the upper horizons. 

It would appear that proximity to the original surface has been favourable to the deposition of 
the high-grade gold-silver ores. The theory that the precipitation of these metals takes place at 
'" critical levels " under the varying conditions of temperature and pressure would therefore receive 
some support from the occurrences on this field. 

Origin of thk Gold and Silvkr. 

The solution of the problem as to the origin of the gold and silver in the ores appears to depend 
largely upon the accurate chemical analyses of an adequate number of samples of the ores and the 
altered and unaltered rocks of the area. The most numerous and reliable analya \ t recorded of the 
Hauraki Peninsula rocks are those cited by Dr. Don* from the soft decomposed and the hard, dark 
andesit's of the .Moanataian Mine. Thames. Briefly stated, these analyses indicate that gold and 
silver do not occur in unaltered andesites. but occur to a greater or lesser extent in all these rocks con- 
taining secondary pyrite. The results of these analyses are in accord with those obtained by Don 
from the rocks of other goldfields of New Zealand and Australia, and have led this investigator to the 
conclusion that " the gold of many lodes of the chief mining districts ot X. -w Zealand. Victoria, and 
Queensland is not due to lateral segregation from the adjacent country rock, but to solutions ascending 
from some rock deeper thai any now exposed at the surface in any part of thi Be colonies." That writer 
adds, " I am not concerned with the question whether this source is the vague ' barvsphere ' with its 
so in, what apocryphal contents of heavy minerals. I have simply to note that a series of laborious and 
careful examinations has failed to find it in the rocks of the ' lithosphere. 1 " 

During the course of the present survey certain volcanic and sedimentary rocks from Coroniandel 
mining-areas were collected by the writers and submitted to the Colonial Analyst lor examination. 
These results, which are withheld until further rocks from the Thames subdivision arc collected and 
examined, are in confirmation of the investigations made by Dr. Don. 

DlSTHIlUTION OK THK Vk.I.NS. 

From the maps it will be observed that mineral veins are of fairly general occurrence throughout 
the subdivision. They are found in certain localities in the Jurassic and Pre-Jurassic stratified rocks, 
abundantly in the " First Period " volcanics, and only OH the eastern side of the main range in the 
" Second Period " volcanics. With the " Third Period " rhyolites are associated only siliceous sinters, 
having no value as ore-deposits. 

Although quartz veins are of such widespread occurrence, mining operations have shown that 
nearly all the more highly auriferous veins occur within the limits of certain fairly well-defined belts. 

(a.) The most important auriferous belt in the whole subdivision is that extending from north 
of Kevin Point (on the shore of Coroniandel Harbour) to and beyond Tokatea Hill and Saddle. This 
belt, which has a trend in an approximated north-north-easterly direction and a width of about a 
mile, includes the Hauraki, Kapanga. and Royal Oak groups of mines, and has therefore produced the 
greater part of the gold of the Coroniandel field. 

* J. K. Don: "The Qene is of certain Auriferous Lodes," Trans. Am. [nst. Aim. Eng., vol. wvii. 



108 

(h.) A parallel belt of lessor importance is that lying about a mile to the south-east of the one 
described. Tins extends from Preece's Point on the shores of Coromandel Harbour through the Success 
and the Old Whangapoua Claims on the main range, to the Four-in-Hand Claim in Kopurukaitai Vallev. 

(c.) A definite belt or zone of mineralisation, but one which has so far afforded no payable mines, 
is that extending from the Moewai Mine, Ngarahutunoa Valley, north-north-east through the 
Owcra. Murphy's Hill, and Materangi Ridge Claims. 

(d.) The Kuaotunu belt of mineralisation, covering the Bald Spur and Waitaia Ridge areas, has a 
trend similar to the last-named (c), and its southerly continuation is probably represented in the minor 
auriferous occurrences of Whauwhau Creek. 

The auriferous areas of the Tiki Hill, Manaia Valley, Opitonui, and the upper Mahakirau Valley 
are not included in any of these belts, and appear to be more isolated. The two first-named of these 
particular areas show considerable lithe-logical resemblances, and would, moreover, fall on a north- 
east - south-west belt. 

The existence, strike, and parallelism of these belts is rather significant, and attention has already 
been drawn to the most important of them (a) by the writings of McKay and Maclaren. The reason 
for such a disposition is not very evident. The prevailing strike of the basement sedimentaries has been 
shown to vary approximately from north-north-east to north-north-west, so that the zones of mineral- 
isation may in certain ca^es correspond approximately to the strike of these strata. Such a correspond- 
ence of mineralisation with general stratification-lines has been observed in Westland.* Apart from 
whether or no such agreement exists in the Coromandel area, the assumption that the gold has been 
derived from deep-seated rocks (see page 107) would imply fracture and Assuring of the basement sedi- 
mentaries now exposed or underlying the andesites along these north-north-easterly belts. 



Detailed Description of Special Areas. 

veins of the colville survey district. 

In the Colviile Survey District no metalliferous veins were located during the course of this survey, 
nor does an examination of the stream-debris favour the opinion that such exist. 

An analysis from certain small stringer veins exposed on the western coast-line some 30 chains 
north of Goat Bay gave negative results for gold and silver. 

VEINS OF THE MOEHAU SURVEY DISTRICT. 

In the Moehau Survey District the geological formation is similar to that of Colviile, and the veins 
located are few and unimportant. 

Hope Creek. — A vein, which has in the past received some attention, occurs on the north-western 
slope of Hope Creek Valley, at an elevation of 630 ft. The old adits are in a state of collapse, 
and little information can be gleaned as to the size and character of the vein. It would appear, 
however, that it occurs in indurated argillites at or near the contact of an intrusion of 
porphvrite. The course of the vein is about east-west and its dip at high angles to the northward. 
Its width is not determinable, but blocks of quartz ranging up to 2 ft. appear on the " dump." Like 
most of the contact veins of the subdivision, the vein-material contains pyrite, galena, and sphalerite. 

A sample collected from the " paddock " yielded on analysis, — p er Ton. 

Oz. dwt. gr. 
Gold .. .. .. .. .. .. ..016 

Silver .. .. .. .. •• •• .. .. 9 14 8 

Value, £1 i)s. per ton. 

Sorry Mary Creek. — In Sorry Mary Creek a small irregular quartz vein, sparsely impregnated with 
similar sulphides to those occurring in the Hope Creek vein, is seen at the contact of intrusive andesite 

* See Heps. U.S., Bulletin .No. 1 (.New Series), Bell and iVaser, 1906, p. 96. 



TO CUr»mp,mj SulUtm N? 4- 




109 

with argillite, about 20 chains from the coast-line. Analysis, however, showed the vein to be of no 
commercial value, — p er 'y on 

Oz. dwt. gr. 
Gold . . .001 

Silver . . . . . . . . . . . . . . 15 

Ohineirai Creek. — Near the head of Ohinewai Creek large quartz boulders occur as " shoadiitgs " 
on the north-western slope of the valley and within the area of altered porphyrites. The quartz is 
coarsely crystalline, and does not bear a favourable appearance lor the existence of valuable metals. 
Analysis indicates a gold-content merely to the amount of 5 gr. per ton. 

Ongahi Creek. — This creek showed no quartz veins, but the grauwacke occurring at the contact of 
a dioritic intrusion was so highly silicified and pyritised that samples were collected for analysis. The 
result, however, which is ;>s follows, is of scientific rather than of economic interest : — 

Per Ton. 
( )/.. dwt. gr. 
Cold .. .. .. .. .. .. ..0 2--) 

Silver .. .. .. .. ..025 

Lead . . . . . . 0-005 per cent. 

A highly altered and pyritised andesite from a lower elevation in the same creek yielded on assay, 

Per Ton. 
Oz. dwt. gr. 

Gold .. .. .. .. .. .. ..ooi 

Silver .. .. .. .. .. ,.00 15 

VEINS OF THE HARATAUNGA SURVEY DISTRICT. 

The veins of the Harataunga Survey District are numerous, occurring both in the argillites and 
grauwaekes of the Moehau Series, and in the andesites and rhyolites of the " First Period." While 
certain of these veins have yielded small pockets of highly auriferous ore, in no case have they afforded 
remunerative returns to any of the companies or private individuals that have exploited them. Accord- 
ing to official statistics, the total value of the gold-silver returns for twenty-five different claims for the 
period 1887-1906 did not exceed £3,000. 

On the general map the positions of nearly all the known veins have been located, and to only 
certain of these need reference be made in the following description 

Vein of Tangiaro ( 'reek. — In Tangiaro Creek, flowing into Port diaries, a vein is exposed at an eleva- 
tion of 75 ft., and at a distance of about a mile and a quarter Lrum the coast. Its course is north-west - 
south-east, and its dip westward at a high angle. The vein, which is] enclosed in a mottled grey 
propylitic andesite, has been drifted on 4 ft. or 5 ft. ; it is well defined and shows a width of 42 in. The 
vein-material is, where exposed, nearly all oxidized to a yellowish-brown colour, but unaltered bands 
and patches are preserved. These show cpiartz containing, in addition to disseminated pyrite, streaks 
of finely divided metallic sulphides, including argentite. The general character of the ore is unlike 
that observed elsewhere in the Coromandel subdivision, and resembles rather that occurring in certain 
veins of the Great Barrier Island, some twenty-five miles to the northward. A general sample taken 

by the writers yielded on analysis, — p er Ton. 

( i/. Hut. gr, 

Gold . . . . . . 22 

Silver .. .. .. .. .. .. .. .. 19 1 5 

Value, £2 Is. 9d. per ton. 

Ore of much higher grade apparently exists, since McKay in referring to this occurrence remarks, 

" Samples of stone taken from a lode 3 ft. to 4 ft. thick have been analysed both at the Thames School 

of Mines and at the Colonial Laboratory, Wellington, the yield in both cases being from 105 oz. to 

110 oz. of silver, and from a trace to 17 dwt. of gold to the ton." * 

It is a matter for surprise that no systematic attempt has vet been made to prospect this vein. 

*C.-9. 1H!)7. p. 57, 



110 

IV/'/i.v oj I hr I'liKingawha Valley (Cabbage Bay). — Within the Umangawha Valley the country 
drained by the Ngakuku, with its branches the White Star and Jersey Creeks, encloses the quartz veins 
of the Harataunga Survey District, which have during recent years received most attention. 

In the White Star Gully the White Star and Killarney veins, striking north-north-west and north- 
east respectively, are the most important yet located. The former averages about 6 in., and the latter 
some 3 ft. in width, both being enclosed in a light-coloured altered rhyolite showing conspicuous pheno- 
crysts of quartz. With the vein-quartz is associated pyrite and arsenopyrite. 

The gold, to the value of about £1,000, obtained by the companies that worked the claim was in 
the main derived from a small steeply pitching shoot in the White Star vein, at its intersection with 
a small stringer. A large quartz vein carrying, it is stated, a little gold, has been intersected in the 
lowest (No. 3) mine-level. The Jersey vein, averaging only about 3 in. in thickness, occurs some 
20 chains to the north-eastward of the White Star, and also intersects rhyolites. A gold-silver return 
valued at £209 is recorded from 10| tons mined from the latter vein during the years 1897-99. 

In Ngakuku Creek several quartz veins varying from 1 in. to 2 ft. in width are exposed at intervals 
in the andesites, for over a mile above the last outcrop of argillites. Pyrite and arsenopyrite are dis- 
seminated throughout the vein-quartz. Of six samples submitted for analysis it is significant that 
none of them gave negative results for gold and silver. The gold ranged from 4'5 gr. to 2 dwt. 12 gr. 
per ton, whilst the silver- content varied from 3 gr. to 1 dwt. 21 gr. per ton. The particular vein show- 
ing the highest value (10s. 2d. per ton) trends nearly north-south (see map), and varies from 6 in. to 
12 in. in width. 

Having regard to the general mineralisation of the veins and the alteration-phase of the enclosing 
andesitic rock, Mr. Allen who examined this area, considers that further prospecting is warranted. 

A vein of some 10 ft. in width, intersecting argillites of Ngakuku Creek, and distant about 20 

chains from the junction with the Umangawha, yielded on analysis, — p er Ton. 

Oz. dwt. gr. 

Gold . . . . 15 

Silver .. .. .. .. .. .. .. . . 15 

Value, 2s. 6d. per ton. 

On the northern slope of Austral Hill, at the bend of the Umangawha Valley, several small veins 
associated with altered rhyolite have been worked in a desultory manner. The veins in these rhyolites 
are less well defined than those in andesites, and are frequently represented only by numerous thin 
parallel stringers. The gold-silver content generally occurs as small isolated " pockets." 

Veins of Matamataharakeke. — In the watershed draining into Waikawau Bay — generally known 
as the Matamataharakeke district — prospecting operations have been carried out intermittently for 
some years past. The auriferous veins located in Cousin Jack and Gisborne Creeks, and in Macaronic 
Gully (Waikanae Creek) have all proved of very small dimensions and unreliable as gold-producers. 
The " First Period " andesites — namely, tuffs and breccias — constitute the country rock, and a few 
" colours " of gold can be obtained in the creek-debris by panning. 

The analysis of a sample from the vein mapped in Matamataharakeke Creek, which is about 

16 in. in width, is as follows : — Per Ton. 

Oz. dwt. gr. 

Gold . . . . . . . . . . . • • • . . 19 

Silver . . 19 

Veins of Mangatu Creek. — Three small veins occur as mapped in Mangatu Creek (Kennedy's Bay). 

A sample assayed from the most westerly occurrence showed, — p er Ton. 

Oz. dwt. gr. 

Gold 1 21 

Silver .. .. .. .. •• •• •• ..016 

Value, 7s. 7d. per ton. 

The remaining two each contained only a few grains of gold and silver per ton. 



Ill 

Veins of Mataiterangi Creek and Bay View Mine (Kennedy's Bay). — Numerous quartz veins, varying 
in width from a few inches up to 10 ft., occur in both headwater branches of the Mataiterangi Creek, 
These veins all occur in an altered andesitic breccia, and, although in some cases pyrite is abundant, 
no gold was detected either by " panning-ofE " tests or by analysis. 

The Bay View Mine, situated near the crest of the range (elevation 780 ft.) at the head of the Matai- 
terangi, was worked intermittently from 1887 to 1899, the value of the gold and silver raised being 
only £156. The veins, which have been mined from four small adits, range up to a foot in width, and 
are associated with what appears to be an altered tufaceous andesite. The payably auriferous ore is 
stated to have existed only as small isolated patches. 

Veins of Omoho Creek. — A small quartz vein exposed in the bed of the ( )moho Creek (Mowing into 
Kennedy's Bay) near the crest of the main range falls within the Harataunga Survey District. This 
vein, which intersects dark thin-bedded argillites, ranges in width from zero to 4 in. or 5 in., and shows 
in places gold associated with the pyrite and slaty selvages. Prospecting operations have resulted in 
a gold-silver return valued at about £100. The hardness of the rock, however, renders the exploitation 
of this narrow lenticular vein expensive. 



VEINS AM) MINIM; CLAIMS OF I'HK HAI'KAKl SPECIAL AREA. 
Locality and General Features of (he Area. 

A ridge of low hills with rounded outlines fringing the north-eastern shore-line of the Coromandel 
Harbour, and the low alluvial Hat skirting the base of these hills, is the locus of the Hauraki group of 
mines. These hills attain a general elevation of 250 ft., and are clothed with a somewhat sparse 
growth of stunted scrub. 

Geological Formation. 

The rocks of this special area, which have vertical extension to and beyond the greatest depths 
yet attained in the mine-workings, are essentially massive and pyroclastic andesites and daeites of 
the " First Period." Associated with these effusives is at least one dyke-intrusion. This dyke — a 
hornblende porphyrite — is probably referable to the " Second Period " of vulcanism It has been 
located in the workings of the Golden Pah Mine, and probably its northerly extension accounts tor 
the " hard bar " existing in the levels driven south from the Union Beach -haft of the Hauraki Mine. 

The greater part of the rocks constituting this mining-area is highly propvlitised. The 
"country*' considered of most favourable character, as being usually associated with the rich ore- 
shoots, is light-grey in colour, with a faint bluisb tint, only moderately hard, and more or less impreg 
nated with tine granular pyrite. The "hard-bars" of mining terminology are in most cases merely 
remnants of less-altered rock, but occasionally, as in the case of the "bar" mentioned in the Golden 
Pah Mine, they owe their existence to mtrusives. The veins and faults, both of which are numerous. 
will be considered in connection with individual mines of this particular area. 

Mining < laims. 

The principal mining claims of the special area (see Map, page 108) are the Hauraki and Bunker's 
Hill, the property of the Old Hauraki (iold-mines (Limited) ; the Welcome Find and Hauraki 
North, the propertv of the Hauraki Freehold Company (Limited) ; and the Golden Pah, Hauraki 
No. 2. and Hauraki South, held by private individuals or svndicates. 

The Hauraki uml Bunker's Hill Mining Claims. 
The Hauraki and Bunker's Hill mining claims, the property of the Old Hauraki Gold Mines 
(Limited), adjoin each other, and are on the same or closely allied veins. The claims occupy a 
central position in the group here considered, and their boundaries and relative positions are shown 
on the accompanying map (page 108). The area of the Hauraki Claim is 28 acres 3 roods II poles, 
and that of the Bunker's Hill 3 acres and 12 poles. 



11 2 

The total value of the gold-silver obtained from these claims up to the 31st December, 1906, as 
compiled from official and other reports, is as follows : — 
Hauraki Mini — 

By Telephone Gold-mining Company (from Union Beach section) — £ 

1871 to November, 1875 . . 25,000 (estimated) 

November, 1875 to 1885 .. .. .. .. 61,245 

.. Coromandel Gold-mining Company, 1886 to 1894 .. .. 459 

„ Hauraki Gold-mining Company (from Hauraki section), 1894 to 

1903 . . . . . . . . . . 893,572 

.. Old Hauraki Gold-mining Company, 1903 to 1906 . . 6,196 

,, proprietors of tailings plant . . . . . . . . 742 

Bunker's Hill Mine- 
By Bunker's Hill and New Bunker's Hill Gold-mining Companies, 

1895 to 1906 .. .. .. .. 17,017 



404,231 



The dividends paid — £ 

By Telephone Gold-mining Company totalled . . . . . . 32,000 

.. Hauraki Gold-mining Company (London), including bonuses, totalled 188,000 

.. Old Hauraki Gold-mining Company totalled .. .. .. 1,250 

.. Bunker's Hill Gold-mining Company totalled .. .. .. 1,333 



222,583 

Mine Development and Equipment. — Access to the underground workings of the Hauraki and 
Bunker's Hill Claims is afforded by three main openings, known respectively as the Hauraki, Union 
Beach, and Bunker's Hill shafts. The Hauraki shaft (size 12 ft. by 8 ft.) has a collar-elevation of 60 ft. 
above sea-level, and a vertical depth of 420 ft ; the equipment consists of a Cornish pump of 12 in. 
diameter, and winding-cages, all operated by steam-power. The Union Beach shaft (12ft. by 8ft.), 
located on the foreshore of the harbour and 1,070 ft. westward of the shaft already described, has a 
collar-elevation of 5 ft., and a total depth of 200 ft ; equipment consists of winding-appliances and a 
disused pumping-engine. The Bimker's Hill shaft (lift, by 3ft. 6 in), located 230ft to the north- 
west of the Hauraki shaft, has a collar-elevation of 125 ft., and a total depth of 290 ft. ; equipment 
consists of a winding- engine, cages, and accessories. 

The main working-levels from the three shafts mentioned, having been driven by different com- 
panies, are not on corresponding horizons. From the Hauraki shaft five levels give access to the 
workings ; the depths of these levels below the shaft-collar are 100 ft, (40 ft.), 160 ft. (100 ft.), 220 ft. 
(160 ft.), 300 ft. (240 ft,), 400 ft. (340 ft.), the numbers in parenthesis indicating the depth of each 
level below high-water mark. From the Union Beach shaft the two levels driven have depths of 80 ft. 
(75 ft.), and 180 ft. (175 ft,). From the Bunker's Hill shaft three levels have been extended at depths 
of 140 ft. (15 ft,), 210 ft, (85 ft,), and 270 ft. (145 ft.) respectively. 

From the main working-levels extended to intersect the veins the latter are exploited and mined 
by the usual methods of driving and stoping. 

The ores raised are all free-milling, and the gold fairly " coarse." The mill on the Hauraki Claim 
consists of a fifteen-stamper battery, Wilfley vanner, berdans, and accessories. The motive power 
employed is steam. 

The Veins.- — An examination of the plan (Map. page 112) will at once indicate that mineralisation in 
the Hauraki and Bunker's Hill Claims has proceeded along numerous lines of rock-fracture, presenting 
a rather complex arrangement. The majority of the veins strike in directions varying from north- 
south to north-west-south-east, and have a prevailing dip to the east or. north-east. Others, however, 
present strikes more or less transverse to those mentioned. Although the formation of all the vein 
fissures would not appear to have been actually contemporaneous, the data available scarcely permit 



/; accompany JRuUetirvJN r £ / 



PLAN OF 

QUARTZ VEINS 
HAURAKI GROUP OF MINES 

COROMANDEL 

Old Hauraki Mine, Bunker's Hill Mine,& Welcome Find 

Section of Hauraki Freehold Mine. 

Plotted at a general level of 50 Feet below a«a level. 



/ 



Welcome Find Section of Hauraki Freehold Mine 



•J T J_ 



Si ..lr .it Feet 



(40 3*0 






/ ' 
/ " 

!, \ 




lona Section 
of Old Hauraki Mine 



fjSqj* 



*. 



<C. 



-X3 









**vr**j SJuft 





JAMES MACKINTOSH BELL 
Hue-, lor 



R« erence 



Reefs it SO Ft hn 

Reefs it ether letel> ._.-_. 

Faults and Cross Courses . 

Sourtdinr 



AT.efc.iw Oovurnmant r,,„i fl 



i 



113 

of any generalisations. The " Cross Lead " and " No. 6 Reef," which are considered identical and 
preserve a north-east - south-west course, would appear, from displacements effected by the trans- 
verse system of veins, to be one of the oldest lines of fracture. The course of the 'Green Harp Reef," 
however, one of the most persistent in the whole area, is peculiar in that it bends round almost at right 
angles, at first exhibiting conformity in strike to one set of veins and then to the transverse set of veins. 
This fact would appear to suggest that mineralisation, if not rock-fracturing, had been contemporaneous, 
or nearly so, throughout this particular area. The nature of the mineralisation, if this be anv criterion. 
also supports this conclusion. 

The veins vary in dimensions from mere stringers to strong ore-bodies 4ft. or 5ft. in width; 
but the majority have an average width of 3 in. to 9 in. They are in almost every case sharply demar- 
cated from the wall-rock, and would appear to be the result of the tilling of narrow fissures formed 
by faulting or contraction. The actual vein-walls are frequently smooth and slickensided, being 
separated from the wall rock by a narrow selvage of plastic finely comminuted rock (locally termed 
"pug"). Occasionally, owing to a local collapse of the walls of the fissures, brecciated rock, subse- 
quently cemented by vein-material, has resulted. " Horses of mullock " may he due to the same 
cause, or to an initial local duplication of the fissure-fracture. 

The primary gangue minerals of the veins are essentially quartz and pyrite. Others which have 
been observed, but only as sparsely distributed constituents, are caloite, hydrous oxides of manganese, 
and arsenopyrite. The quartz is usually compact, finely crystalline, and of a bluish-white colour. Drusv 
cavities lined with small prisms of quartz, terminated by pyramidal faces, are abundant. The pyrite 
which has been deposited contemporaneously with the quartz is usually finely granular, that occurring 
in the druses either granular or cubical. 

The gold present in the ore is invariably associated with silver as an electntm, containing on the 
average 74 per cent, of gold and 26 per cent, of silver by weight. This corresponds roughly to the 
formula Au ; , Ag 2 (Au, ; Ag 4 ). In almost all the payable ores, whether they are in a state of oxidation 
or not, the gold is visible megascopic-ally. It usually occurs as coarse jagged particles or dichotomously 
branching filaments throughout the general mass of the quartz 

The payable ore of these mines occurs in the veins as Bhoots or pockets, variable in extent and 
disposition. In these bonanzas, ore worth "three ounces to the pound" (that is, ore containing 
."> ounces (troy ) of gold per pound advoirdupois) is not uncommon, and many tons ol ore have been won. 
averaging over "an ounce to the pound." The general mass of the vein-material associated with 
bonanzas and lying within the limits of the ore-shoots is pavablv auriferous, while that of the vein 
beyond the limits of these shoots is either non-auriferous or so low in gold-content as to be of no com- 
mercial value. 

The north-west - south-east trending veins and branch veins na Iv. "" Legge's " (No. I, Hunker's). 

" New Year." "No. 3," " NO 7," and "Green Harp." show a general agreement in the disposition 
of their ore-shoots. These shoots, though differing considerably in extent, nearly all exhibit a pro- 
nounced pitch to the north-west. A line drawn at right angles to the general trend of the vein-system, 
at a certain point would intersect many of these bonanzas, hence the phenomenon described as 
" ore to ore " is here well exemplified. 

The greatest ore-shoot yet discovered in these claims was thai of the No. 2 or " Legge's Reef." This 
shoot measured 150 ft. in width, and extended from the surface of the solid propvlitised andesite to 
a depth of about 260 ft. Its pitch to the north-west corresponded to the inclinations of the inter- 
sections of the No. 3 vein and the " Cross Reef No. 2." The intersecting veins, veinlets, and cross- 
courses have exercised an influence not only on the position of the great ore-shoot of this vein, but on 
that of the shoots and pockets of bonanza ore in each of the veins. The occurrences of the various 
patches of rich ore in both the " Green Harp " and the " No. 6 " veins aptly demonstrate this 
influence of intersecting veins and fissures on the deposition of the gold. Between these planes of inter- 
section long stretches of the veins have been allowed to remain intact, as unpayable to exploit, although 
there is, of course, no certainty that other shoots remain undiscovered in these particular blocks. 

The north-south-trending vein, " Iona No. 2," of the Hauraki Claim has in part been termed the 
'" Iona No. 3 " on the mine-plans, owing to displacement by a fault -fissure, and is further known as 
8— Coromandel. 



114 

the " Tribute Lode " in the Bunker's Hill Claim. The vein has been traced for a total distance of 
340 ft., passing from the Hauraki Claim through the Bunker's Hill and into the Welcome Find Claim. 
It varies from a few inches to 4 ft. in width, and dips at an angle of 40° or less. The vein differs from 
the others of the area only in its low inclination and in the general horizontality of the discovered ore- 
shoot. This shoot occurred at a depth of some 40 ft. below sea-level (100 ft. below the collar-level 
of Hauraki shaft), and continued throughout the whole exploited length of the vein. This ore-shoot, 
unlike those of most of the other veins of the system, was unaffected either in horizon or in tenor by 
a fault-fissure (" Iona No. 1 ") which caused a 35 ft. horizontal displacement of the vein. A fault with a 
southerly hade in the vicinity of the north-east corner of the Bunker's Hill Claim has here terminated 
this consistent gold-bearing vein. This faulting has effected a considerable " drag " of the vein to the 
eastward, a fact which sufficiently indicates where its displaced portion should be found. 

The No. 7 and " Green Harp " veins of the Hauraki Claim would appear to have junctioned in 
the Bunker's Hill Claim. At and in the vicinity of this intersection bonanza ore was discovered, and 
is reported to have continued as a nearly vertical shoot to and beyond the greatest depth exploited. • 

The Faults. — The post-mineral or non-mineralised fractures are in this area almost as numerous 
as the veins. They are in almost all cases fissures filled, as the result of rock-movement and decom- 
position processes, with clayey material (" pug "). Frequently they afford very effective barriers 
to the circulation of the ground-waters, or, again, are more open and permeable. 

The main faults, it will be observed from the map (page 112), show a general parallelism and 
a north-west - south-east strike. Those existing to the north of the Bunker's Hill shaft hade to the 
south-west, those to the south of the shaft hade to the north-east. This would suggest step-faulting, 
both from the north and the south towards this shaft. It would seem certain, however, from the dis- 
placements of the veins that each successive block of country, considered in order from south to north, 
has been displaced to the eastward. A recognition of this fact has an important bearing on the recovery 
of " lost " veins. 

Future Development. — An expression of opinion as to the directions in which future mining opera- 
tions might be extended with a reasonable hope of success, must, in the absence of more specific data, 
be based on somewhat general considerations. 

The advisability of the further exploitation of " Legge's," the " Hauraki No. 7," and the " Green 
Harp " veins below the present workings of the Bunker's Hill Mine may be suggested. This follows 
on a consideration of the probable northerly dip of the productive propylitic zone of the Hauraki 
Mine and of the pronounced pitch of the exploited bonanza ore-shoots in the same direction. The suc- 
cessive downthrows to the north-east of the several faulted blocks of " country " lying to the north 
of the Bunker's Hill shaft also favour the prospect of " deeper ground " on this propylitic zone in the 
locality indicated. 

The recovery of certain veins which carried high-grade ore, and were abruptly terminated by 
faulting, would also appear warranted. Chief among these is the Iona No. 2 vein, which on the north 
side of the fault should be found in the Iona section of the Hauraki Mine. 

As in all mining properties of this particular character, the policy of advancing prospecting cross- 
cuts through the relatively large undeveloped areas in the proved zone of mineralisation cannot be too 
strongly recommended. 

It is a matter for surprise that in an area which has yielded bullion to the value of over £400,000 
the deepest workings have attained no greater depth than some 400 ft. below the present caps of the 
veins ; this notwithstanding that bonanza ore comparable with that obtained from the surface-levels 
has been mined from a depth of nearly 300 ft. Quite irrespective of the results which may attend 
further mine-development in the upper propylitic zone, the sinking of the Hauraki shaft in the hope 
of intersecting another ore-bearing horizon is certainly a legitimate prospecting proposition. There 
is every likelihood that the andesites of these and the neighbouring mining claims will extend to 
considerable depths, judging by the conditions obtaining in the Kapanga Mine, which is nearer the 
outcrops of the basement sedimentaries. 



o afoifoj 



i yn.inD// 






rsAtuJtJjj 



X><? KDl/ou 



U.'U ^"V'Ty 







o m 



— ^ 
1 3 



- a 



x 



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115 

The Welcome Find Claim and Hauraki Freehold. 

The Welcome Find Claim and the Hauraki Freehold, which are together held by the Hauraki 
Freehold Company (Limited), lie to the northward of the two claims just described. Map, page 
108, shows the relative positions of these mines ; map, page 112, on an enlarged scale, the Welcome 
Find Claim (area, 8 acres 1 rood 8 poles) and its principal veins. 

The principal access to the underground workings is afforded by two openings — the Welcome 
Find and the Hauraki North shafts. Equipment on the former shaft comprises a small Cornish pump 
and a pair of winding-cages, operated by steam-power ; that on the latter shaft, a pair of winding- 
engines operated by a rather meagre water-power. 

The greater part of the gold-output of these claims is referable to the early days of the field. Since 
1895 the vsdue of the gold and silver won amounts to £8,898. 

The greatest depth to which mining operations have been advanced in these claims is 230 ft. below 
the surface. In the Welcome Find Mine two other levels exist at elevations of 60 ft. and 100 ft. 
respectively above the low level. 

The veins, together with the occurrences of the pay-ore, differ in no respect from the general type 
of those in the Hauraki and Bunker's Hill Claims, and must be regarded as belonging to the same 
system. Faulting is here, as in the adjoining claim, a prominent feature, and has the usual influence 
on the position of the ore-shoots. Precise information as to existing economic conditions in these mines 
was not available to the writers, on account of a temporary cessation of mining operations. The sugges- 
tions made in respect to future operations in the Hauraki and Bunker's Hill Mines, however, have a 
general applicability to the mining-claims here considered. 

The position of the claims, their areas, and the results which have from time to time attended the 
operations already carried out, warrant further exploitation on the present levels, and in the unknown 
areas of greater depths. 

Golden Pah, Hauraki No. 2, and Hauraki South Mining Claims. 

The Golden Pah, Hauraki No. 2, and Hauraki South Mining Claims all lie in the southern portion 
of this special area. Maps, pages 108 and 101, show the claim-boundaries and the veins that have 
been mapped. The total gold-output of the claims is small, but the actual figures are not available. 
Access to underground workings is afforded by adits and shafts; but the latter are in a state of disuse, 
and the machinery has in most cases been dismantled. 

In the Golden Pah Claim certain veins have at times afforded small pockets of rich bonanza ore, 
while oxidized propylitic andesite containing numerous reticulated quartz veins has been mined from 
certain localities above the ground-water level, and milled for its gold-content. 

In the Hauraki No. 2 Claim a considerable amount of work has been done from adit levels. Veins 
probably identical with certain of those in the Hauraki Mine have been prospected, but no ore- 
shoots of any importance have been located. 

In the Hauraki South Claim a fairly substantial shaft was sunk some years ago by an English 
company, but little prospecting-work below the ground-water level was undertaken. The rock 
encountered in the shaft itself did not exhibit the phase of alteration usually associated with the pay- 
ably auriferous veins of the Hauraki group of mines. 



THE VEINS AND MINING CLAIMS OF THE KAPANGA SPECIAL AREA. 

Locality and General Features of the Area. 

The Kapanga special area is located among the foothills of the western base of the Tokatea Hill, 
and lies nearly midway between the Hauraki area already described and the Tokatea area to be con- 
sidered later. This foot-hill country, covered with a stunted growth of manuka and fern, varies in 
elevation from 200 ft. to 300 ft., and is incised by several small tributaries of Whangarahi Creek. 
8* — Coromandel. 



116 

Geological Formation. 

Tertiary andesites and dacites of the " First Period," in the form of tuffs, breccias, and lava- 
flows, constitute the rocks of this area to and beyond the greatest depths yet exploited. The general 
disposition of these volcanics and the various zones of propylitic alteration have already been described 
(see page 100). The relatively great depth to which the andesitic rocks have been proved to 
extend in the Kapanga shaft has occasioned some surprise in view of the fact that the basement sedi- 
mentaries outcrop within 50 chains of the shaft. A movement of subsidence has, however, been 
recorded in the Kapanga area by the coal-seam existing at a depth of 940 ft. below the present surface 
(700 ft. below sea-level). On the supposition that this movement was a differential one, due to faulting 
along the western base of Tokatea Hill, the relative positions of the volcanics and the older rocks is 
readilv explainable. The extraordinary pressure of the ground that was encountered in the sinking of 
the Britannia shaft, at the western base of Tokatea, would also suggest the presence of a fault in this 
vicinity. 

Between the Kapanga area and Kikowhakarere Bay, lying to the westward, the " First Period " 
volcanics — -auriferous series — are flanked and overlain by the rocks of the Beeson's Island Series, 
which, both here, and wherever encountered on the western side of the peninsula, are non-auriferous. 

Mining Claims. 

The principal mining claims of this special area are the Old Kapanga, the property of the Old 
Kapanga Gold-mining Company (Limited), and the Old Scotty's, the property of the South Kapanga 
Gold-mining Company (Limited). Other areas of lesser importance are held by these companies and by 
private individuals. 

The Old Kapanga Claim. 

The Old Kapanga Mining Claim (area, 25 acres 3 roods 8 poles), which is now the property of 
the Old Kapanga Gold-mining Company (registered in Auckland), was for the thirty-four years prior 
to 1906 owned and worked, together with certain adjoining ground, by an English companv. 
Map, page 108, sets forth the position of the claim, and its past and present boundaries. 

The value of the gold-silver production prior to the year 1864 is not recorded. That of sub- 
sequent years, compiled from official and other reports, is as follows : — 

By Kapanga Gold-mining Company (Auckland), 1864-69 . . . . 122,419 



Kapanga Gold 
1872-85 
1886-90 
1890-98 
1898-1906 



mining Company (London)- 



11,380 

33,461 

29,249 

8,394 



Total .. .. .. .. .. .. 204,903 

The amount paid in dividends is not recorded. 

Mine Development and Equipment. — Access to the underground workings is afforded by one main 
shaft, and there also exist two or three disused shafts connected with the upper workings. Numerous 
adits, now in a state of collapse, were driven from the various small gullies in the early days to 
exploit the veins above the ground-water level. The main shaft (size 14 ft by 9 ft.), with a collar- 
elevation of 240 ft. above sea-level, has been sunk to a depth of 1,000 ft. This shaft, at a depth of 
520 ft. to 600 ft., intersected the Kapanga and Scotty's veins, dipping westerly from their points of 
outcrop some hundreds of feet to the east of the shaft's mouth. 

Above these levels the veins were exploited from crosscuts driven eastward at depths of 300 ft., 
420 ft., and 500 ft. respectively. In addition, drives, to which further reference will be made, have been 
extended at the 600 ft., 700 ft,, 800 ft., 940 ft., and 1,000 ft. levels. 



117 

The machinery employed in carrying out the mining and milling operations included a 15 in. 
plunger and draw-lift pump, winding-equipment, and a ten-stamp batten' — all operated by steam- 
power. The whole of this, however, was recently dismantled and removed. The present proprietary 
company has installed a small pumping and winding plant, to permit of certain work in the upper levels 
of the mine. 

The Veins. — The veins of the Old Kapanga Mine comprise the Kapanga and Scotty's. with their 
various branches, also Hartridge's, Anniversary, and several which are not named. 

The Kapanga and Scotty's veins, which have yielded nearly all the gold of this mine, show in the 
upper levels a general parallelism both in strike and dip. The strike of each vein is decidedly serpentine. 
but in general direction does not vary greatly from north-south (see map, page 1 18). The westerly dip 
varies in each case from 25° to 35°, the low angles being more characteristic of Scotty's vein. The trend of 
the Kapanga vein at and below the 420 ft. level, as the plate will show, exhibits variations from that of 
the upper levels. Below the 600 ft. level the dips of the Kapanga and Scotty's veins arc at considerably 
higher angles than those mentioned. The change in the vein fissures from low angles to fairly high 
angles corresponds with the change in the country rock from fairly soft propylitic andesite to harder 
less-altered andesite. This would imply alternation of softer and harder rock at the period of rock- 
fracture, the fissures in the harder rock being deflected towards the directions of least resistance. 

In the 1,000ft. level, where the lower zone of prupvlitic andesite has been entered, neither the 
Kapanga nor Scotty's vein has been identified, although the crosscut has been advanced beyond where 
they were expected to have occurred. In this low-level zone were discovered Hartridge's, the Anni- 
versary, anil other veins, none of which were identified m the upper levels of the mine. These veins 
of the lower levels, moreover, strike almost at right angles To the Kapanga and Scotty's veins. It is 
impossible from the meagre data obtainable to account for this apparent unconformity in the vein 
systems of the upper and lower levels of the mine. In this connection, however, regard must be had 
to the old land-surface (coal-seam), which marks an unconformity in the andesitic accumulations, 
but the writers cannot definitely assert that Hartridge's. Anniversary, and the other veins terminated 
on their upward extension at this old land-surface. 

Tin- vein-material, which was apparently deposited in narrow, open fissures, consists in the main of 
quartz, pyrite, and occasionally calcite. The gold and silver, alloyed in the ratio of about 100 : (•'$, 
occurs with this gangue mainly as shoots and patches of t he bonanza type. Native arsenic and arseno- 
pyrite are common associates of the highly auriferous vein-stone. It has also been noticed, remarks 
.Maclaren. "that a green discoloration of the country often precedes the discovery of rich quartz — a 
colour due probably to melanterite or iron-sulphate." * 

The bonanza ores of both the Kapanga and Scotty's veins are said to have occurred at the planes 
of intersection of the small cross-veins, or loop-veins, and also at points of marked local irregularities 
— elbows and bends — in the veins themselves. Strong pvritic mineralisation of the wall-rocks almost 
always accompanied the richest ore-shoots. The highly auriferous ore of the Kapanga and Scotty's 
veins had extension, though not continuous, from the outcrops to a depth of some 450 ft. This ore, 
in passing from the vein-outcrops to the depth quoted, while showing diminution in quantity, cannot 
be affirmed to have shown diminution in gold-content. 

In Hartridge's vein (9 in.) patches of bonanza ore, rather small in extent but comparable in tenor 
with those from veins of the upper levels, occurred at the 940 ft. level. The largest of the patches 
was found near the main shaft, where the vein came in contact with the flat-lying coaly seam already 
mentioned. The precipitation of the gold at this point was evidently effected bv the great masses of 
pyrite. which occur in this seam as the result of the reducing action of carbon. (Jold has been detected 
in the actual seam or " mineral bar " as isolated coarse grains in association with quartz ; but an 
analysis of a general sample from the pvritic mass on the surface " dumps " gave negative results for 
gold and silver. 

*(\-9, 1900, j>. 16. 



118 

Future Development. — With regard to the resources of the milling property, the available data 
permits only of somewhat general considerations. The Kapanga and Scotty's veins, worked for over 
forty years, must in the upper mine-levels be regarded as almost completely depleted of their ores ; 
small loops and branches of these veins carrying pockets of highly auriferous quartz may, however, be 
discovered from time to time, as recent experiences have demonstrated. It cannot be ascertained 
from examination of the mine-plans to what extent prospecting crosscuts within this productive propy- 
litic zone have been advanced. The extension of the adit level from the low grounds of Kikowhakarere 
Bay to the Kapanga shaft has from time to time been advocated as a means of permanently draining 
and opening-up for prospectors a considerable area of country, and also affording a roadway for the 
cheaper delivery of fuel and mining-material to the several claims. The scheme is certainly a feasible 
one, although no discoveries of auriferous veins can be anticipated within the belt of the Beeson's 
Island volcanics, which extends from the coast-line for about half a mile in' and. 

The hopes of the proprietary company are centred on the low levels of the mine, owing to the proved 
existence of the zone of highly propylitic rock extending from the 940 ft. level in the shaft to and 
beyond a depth of 1,225 ft. (the bottom of the borehole sunk from the 1,000 ft. level in shaft). At 
the 940 ft. level the limited amount of work done on Hartridge's reef has demonstrated the fact that 
patches of bonanza ore do exist in the propylitic zone. Again, from an unspecified level in the bore- 
hole crushed pyritic material was, during the progress of boring operations, submitted to the senior 
riter for analysis, and yielded gold and silver equal to a value approximating £5 per ton. 

Increased depth usually implies a lesser concentration of the gold-silver content of veins. While, 
therefore, in the low levels bonanza ore-shoots may exist where conditions favourable to their formation 
have obtained, the precious metals may generally be found more evenly disseminated throughout the 
vein-material. The results of treatment of the ore from Hartridge's vein support this conclusion. 
Returns, not inconsiderable, were obtained by the ordinary battery-amalgamation process from ore 
from this vein which showed no visible gold. In the upper-levels, vein-material in which no gold could 
be seen seldom or never yielded sufficient to cover the cost of treatment. 

It will be inferred from the facts submitted that further exploitation of the Kapanga Mine is 
desirable in the deeper horizons, which exhibit pronounced alteration of the country rock by hydro- 
thermal agencies, with an attendant strong general miner ahsati on. 

The ground-water conditions existing in the Kapanga Mine, as revealed by pumping operations, 
are of both scientific interest and of economic importance. From the original water-level to a depth 
of about 550 ft. (310 ft. below sea-level) the amount of water to be raised was considerable. Below 
the 550 ft. level it is stated the volume showed rapid diminution, and at the 1,000 ft. level, (760 ft. 
below sea-level), became almost a negligible quantity. 



Old Scotty's Mining Claim. 

Old Scotty's Mining Claim, the property of the South Kapanga Gold-mining Company, has 
been worked on the northward extension of Kapanga and Scotty's veins from the Old Kapanga 
Mine, and on minor veins closely related to these. The gold-silver returns for the earlier period of 
the mine's existence are not available ; but for the period 1891-1906 the value of the total output 
only amounts to £3,520. Maps, pages 108 and 104, show the position of the claim and the veins which 
it encloses. 

Other Areas. 

The areas lying to the north-east and south of the claims mentioned enclose numerous veins, 
which have in former years been exploited by various companies and private individuals. Of these 
veins Murphy's and the Flying Cloud may be mentioned as having yielded, near the surface, patches 
of bonanza ore. The characteristics of these veins are in the main the same as those of the Old 
Kapanga Mine. 



Tc accompany Bulletin N$ 4- 




PLAN SHOWING 

THE PRINCIPAL REEFS 

wm ttw *wm mm 

COROMANDEL 

Scale of Feet 

I 50 O IO< 



Different Levels shown by colour as under. 
300 F- T . 4Z0F* 800FT 900FT 940F? 1000 F* RISES 

□ □ □ □ i 

Reefs shown thus . '— 



Drawn, try R.J.Cra-w ford, August 1907. 



Authority : John Mackay, Government Printer, 



119 



THE VEINS AND MINING CLAIMS OF THE TOKATEA-SUCCESS RANGE. 

Locality and General Features of the Area. 

The Tokatea-Success Range may be considered as that stretch of the main divide extending 
southward from a point 40 chains north of Tokatea Hill to the Whangapoua Saddle. The most 
prominent heights on the range are Tokatea Hill (1,577 ft.), Trigonometrical Station UU (1,852 ft.), 
and Kaipawa or Success Hill (1,935 ft.). Tokatea Saddle has an elevation of 1,200 ft. The range- 
flanks, which are in the main fairly steep, are incised by several small streams draining to either 
coast-line, and support a vegetation consisting in places of light mixed bush, and elsewhere of scrub 
and grasses. 

Geological Formation. 

As the geological ma]) and sections will show, the basement or core of the whole of the Tokatea- 
Success Range consists of rocks of the Tokatea Hill Series — argillites and grauwackes, with 
interstratified volcamcs of acidic character. These folded and denuded strata were covered by the 
Tertiary andesites of the " First Period " — tuffs, breccias, and lavas, the fragmental rocks pre- 
dominating. These old interstratified volcanics are, owing to denudation, exposed on the actual crest 
of the range at Tokatea Hill and Saddle, and on both flanks of the range at certain localities. 
The Tokatea Hill Series in this area is largely intruded by dykes of porhpyrite, and in one locality on 
the eastern flank of Tokatea Hill by a dyke of rhyolite. Some of these porphyrite dykes may also 
intersect the overlying Tertian' andesites, but the alteration and weathering of the rocks renders detec- 
tion of the dykes difficult. 

Reference has already been made (page l(Ht) to the alteration by thermal waters of the andesites 
(propyhtisation) and of the older rocks. 

The Veins. m 

The veins of the Tokatea-Success Range comprise (a) the Tokatea " Big Reef " ; (b) the veins 
of the Tokatea Hill and vicinity, subsidiary to the " Big Reef " but of much greater economic 
importance ; (c) the veins of Success Hill and vicinity, related to the " Big Reef," as are those of 
group (6). 

(a.) Tokatea "Big Reef." 

The Tokatea " Big Reef '" i- the largest vein occurring not only in the particular area under 
review, but in the whole of the Coromandel subdivision. It varies approximately from 30 ft. 
to 150 ft. in width ; strikes about north-and-south and dips west at an angle of 45°-65°. The 
vein forms a conspicuous feature of the landscape, stamUng out in places as a white wall, and 
covering the slopes of the range with " shoadmgs " of quartz boulders. The most northerly out- 
crop occurs some few chains to the north of Tokatea Hill where the vein is almost coincident with 
the crest of the range. On tracing its course southward from Tokatea Hill the " Big Reef " descends 
on the western slopes of the range. At a point just northward of Courthouse Creek, where it attains 
probably its maximum thickness, the vein bifurcates, one branch striking south-east and the other 
south. The more westerly branch, or that trending south, appears to vary considerably in width, 
and its outcrops only appear at intervals. The most southerly outcrop is found in the bed of Cadman 
Creek, 6 chains above the water-supply dam, where the vein has a width of perhaps 40 ft. The branch 
trending south-east maintains a width averaging 40 ft. to a point some 12 chains south of the Success 
Road, beyond which it becomes much attenuated. 

The Tokatea " Big Reef " intersects both the Tertiary andesites and the basement sedimentaries 
On the high western flank of Tokatea Hill and in Maddern Creek it appears to lie at or near the con- 
tact of the andesites and the strata of the Tokatea Hill Series. Further south it is almost alwavs found 
associated with the andesitic rocks. This vein, however, in the No. 7 level of the Royal Oak Mine 
(Tokatea) and its westerly branch in Cadman Creek are both associated entirely with the argillites and 
grauwackes of the Tokatea Hill Series. 



120 



The rein-material is in the main the result of fissure-filling, but where the wall-rock consists of 
andesite the hanging-wall portion is largely the result of the replacement of that rock. White crystalline 
quartz exhibiting numerous drusy cavities, and containing a very small percentage of pyrite and. 
occasionally, hydrous oxides of manganese, constitutes the vein-filling. Sparsely distributed galena 
and copper-pyrite are ocasionally present where the vein occurs at the contact of andesites and argillites. 
The decomposition of the vein-material by surface waters has resulted in the conversion of the pyrite 
to hydrous oxides of iron, which impart a brownish staining to the whole mass. 

The opinion has been sometimes expressed in mining circles that the Tokatea " Big Reef " has 
some prospective economic value on account of its gold-eontint, and a few trial crushings from certain 
points are cited as having yielded returns of from 1 dwt. to 4 dwt. of gold per ton. With the object 
of ascertaining its actual gold-silver content the vein was made the object of special investigation 
by the writers, and a careful sampling was undertaken at points which offered the best facilities. In 
the Tokatea area the vein is well exposed in the bed of the Whakaroa Creek, just below the " tip-head " 
of the Harbour View low-level. Samples selected from wall to wall of the vein, which at this point 
measures about 60 ft., were shown by analysis to contain no trace of gold or silver. 

Further south the vein, or a branch of the vein where intersected by Courthouse Creek, showed, in 
addition to pvrite, a small percentage of galena and chalcopyrite. Sampling and analysis of the vein- 
material revealed no trace of gold or silver. 

The south-eastern trending or main foot-wall branch of the " Big Reef," which boldly ouctrops on 
Success Hill, was examined in detail on account of a prevailing general impression that at least this 
portion of the " Big Reef " had a potential value as a low-grade ore-deposit. The prospecting operations 
undertaken some years ago by an English company — the New Hauraki Gold Properties (Limited) — 
afforded special facilities for ascertaining the value of a considerable extent of the vein. A drive has 
been advanced from the Success Road for a distance of 1,200 ft. along the footwall and at a depth of 
some 200 ft. below the highest point of outcrop. From this drive the vein itself has been crosscut 
or partly crosscut at various intervals. Throughout a distance of 800 ft. from the mouth of the drive 
these crosscuts show the vein to have an average width of 40 ft., but from here southward a gradual 
" feathering out " longitudinally is apparent. At each of the twelve crosscuts heavy samples were 
broken out from foot-wall to hanging- wall, or (where the hanging-wall was not exposed) from the foot- 
wall to the end of each crosscut. The vein-material from each 10 ft. interval of these cross-sections was 
tested separately. Each sample was reduced by crushing and quartering, the portion not required for 
analysis being reserved for the ordinary " panning-off " test. As the result of these operations twenty- 
four samples were submitted for analysis. 



1 sample yielded 

2 ,, „ a 

3 „ 

i >> >> 

3 ,, „ 

10 „ 



Gold per 
Ton. 
Gr. 
.. 2 


Silver per 

Ton. 
Dwt. gr. 

13 


1 


1 4 


1 


14 


1 


fi 


1 


3 


.. 


8 


.. 


7 


.. 


4 



No trace of gold or silver. 



24 



Panning-off tests, which in the examination of oxidized vein-material are thoroughly reliable, showed 
no " colour " of gold in any of the above samples. In addition to confirming the laboratory analyses, 
these tests showed that the vein-stuff contained no coarse grains of gold which might have escaped 
inclusion in the assay samples. 



121 

From a drive on the vein situated between the southern end of the main level above described 
and the outcrop, three general samples were selected, all of which gave nil results for gold and silver. 

The southern trending or hanging-wall branch of the " Big Reef " has been crosscut in a drive 
from the Success Road. Three heavy general samples were broken out and sampled down for analysis. 
Each afforded nil results for gold and silver. 

A general sample taken from the southern continuation of this branch of the " Big Reef " where 
it crosses Cadman Creek (width here perhaps 40 ft.) yielded on analysis— gold, nil ; silver, 1 dwt. 6 gr. 
per ton. 

The above results show unmistakably that the Tokatea " Big Reef " has, at least in the particular 
localities investigated, no economic value as an ore-deposit. It may be further remarked that these 
particular localities — Tokatea and Success — are those in which occurred the highly auriferous sub- 
sidiary veins of the system. In other words, the localities are those in which the Tokatea " Big Reef " 
traverses the ascertained auriferous belts. 

It would appear, from the resu.ts submitted and also from an inspection of some of the under- 
ground workings, that the bulk " parcels " mined and milled from the " Big Reef " with a view to 
ascertaining its value by battery tests, were not representative. The bulk samples consisted almost 
entirely of the silicified propylitic andesite seamed with reticulated quartz veinlets, which tonus the 
hanging-wall rock of the " Big Reef." 

The only available information regarding the character oi this vem m the deeper mine-workings 
was afforded by the No. 7 level of the Royal Oak, which is 930 It. below the outcrop oi the " Big Reel 
on Tokatea Hill and 647 ft. above sea-level. Examination of the vein, which at this point intersects 
black drossy argillites, was precluded by collapse of the adit level. It is, however, stated on reliable 
authority that it is here represented by a fissure containing much " mullock " and clayey material 
and very little quartz, the latter carrying no gold-silver values. 

(b.) Veins <</ Tokatea Hill and Vicinity. 

The veins oi the Tokatea Hill and the immediate vicinity differ from those of the Success 
group further southward, and also from those of the Hauraki and Kapanga special areas to 
the westward, in that they are associated with the strata ol the Tokatea Hill Series rather than 
with the Tertiary volcanics. The felsitic tuffs and tufaceous mudstones, which are mterstratified 
with the ordinary grauwaekes and argillites ot this series, constitute the country rock con- 
nected with the more productive portion of the veins. The principal veins are here described in 
connection with tin' mining claims in which they are located. The claims at present in existence 
are — the Royal Oak and Tokatea, the properties of the Royal Oak Gold-mining Company (Limited) ; 
the Harbour View and Pride of Tokatea (old Hauraki Associated), the properties of the Harbour View 
Gold-mining Company (Limited) ; the New Tokatea, held by a company of the same name ; the Queen 
of the North (Monte Cristo) and other areas held by private individuals. The areas of these claims 
and their relative positions are indicated on Map, page 108. 

A rather significant fact, and one which has been noted by previous writers, is that the area at 
Tokatea, from which nearly all the gold has been won, lies between the Tokatea "Big Reef" and the 
rhvolite dyke existing some 20 chains to the eastward. Both the " Reef " and dyke trend approxi- 
mate^- north-and-south and dip to the westward. This area appears furthermore to be limited to the 
northward by one of the bands of rhvolite which appears mterstratified with the Tokatea Hill Series 
in the gorge of the Harataun^a, and strikes in the direction of the Queen of the North Claim near the 
crest of the range. 

Royal Oak and Tokatea Claims.— The Royal Oak and Tokatea Claims together include within their 
boundaries the actual summit and a portion of the eastern and western Hanks of Tokatea Hill (1,577 ft.). 
They are the claims which have yielded the greater bulk of the gold of the Tokatea area. The 



122 

following figures, as the value of the gold and silver obtained, are much more likely to be under than 
over the actual amount : — 

From Tokatea Claim — £ 

By Tokatea Gold-mining Company (Auckland), September, 1869-1885 150,286 
„ Tokatea Gold-mining Company and others, 1886-97 . . . . 9,588 

From Royal Oak Claim — 

By Royal Oak Gold-mining Company (Auckland), September, 1871— 

1885 .. .. .. .. .. .. .. 22,903 

By Royal Oak Goldmining Company (Auckland 

„ Royal Oak of Hauraki (London) 

t> i r» i n u /a ii j\ V1886-1906 .. 95,903 

„ Royal Oak Gold-mines (Auckland) 

And others 



278,680 



Dividends reported as paid — 

By Tokatea Gold-mining Company (Auckland), totalled . . . . 63,625 

„ Royal Oak Gold-mining Company (Auckland) to 1885 totalled . . 6,210 

„ Royal Oak of Hauraki (Limited), totalled . . . . . . . . 12,500 



82,335 

Access to the mine- workings is afforded by adit levels entering from the easterly slopes of the hill. 
There are seven of these main adits, the lowest (No. 7) being 930 ft. below the crest of Tokatea Hill 
and 647 ft. above sea-level. From the floor of this level, at a point about 1,850 ft. from the entrance 
and vertically below the crest of the range, a shaft has been sunk to a depth of 160 ft., and from this 
shaft a limited amount of driving and stoping has been done. Notwithstanding that the mine has 
been exploited from adit levels, operations have proved costly, more especially in the lower levels, on 
account of the hardness of the rock enclosing the veins. Rock-drills driven by compressed air have 
in more recent years been employed in the mine-development. The air-compressors transmitting 
power to the drills and also to the battery were located at the eastern base of the range, and were driven 
by water-power derived from certain branches of the Harataunga Stream. The rather meagre and 
varying water-supply and the high cost of general working-expenses has led to the abandonment of the 
scheme and the removal of the machinery. The company's battery comprises twelve stamps and 
eight berdans, the power, since the removal of the air-compressor plant, being supplied by an oil- 
engine. 

The principal veins of the Royal Oak and Tokatea Claims are the " Tokatea," " No. 1 " or " Tri- 
bute," " No. 2," " No. 3," " Swedish Crown," " Alpine," and " Excelsior." All of these occur on the 
foot- wall side of the " Big Reef." 

The " Tokatea " and " Tribute," which have proved by far the most productive of the veins named, 
strike respectively east-north-east and east from the " Big Reef," the " Tribute " occurring about 240 ft. 
to the southward of the " Tokatea," and, like it, dipping at high angles to the southward. 

Quartz, calcite, and pyrite form the principal gangue- minerals, but the hydrous oxides of manganese 
are in places not uncommon. The calcite exists in much greater quantity than in the veins of the 
Hauraki and Kapanga Mines, a fact which is doubtless due to the different nature of the country rock. 
The gold occurs with silver in the average proportion of 100 to 50 by weight ; the latter metal is there- 
fore more abundant here than in most of the veins connected with andesites. 

The bonanza ore has been found to occur as definite shoots and irregular patches. In the upper 
levels of the mines the ore-shoots are said to have been intimately associated with what are termed 
" mineral heads " or " bars." These are apparently layers of the sedimentary rock, which originally 
proved more permeable to the circulating ground-waters than the general mass of the rock, and supplied 
aqueous precipitants of gold and silver to the vein-channels. These " mineral heads " now carry a 



To accompany Bulletin JV & 4< 




By Authority : John Mackay, Gouernment Pnnte< 



1-23 

high percentage of pyrite, cherty silica, and a clayey material, and often present a greenish coloration 
which may be due to sulphate or silicate of iron. In the lower levels the patches of highly auriferous 
ore generally occurred at the intersections of " flinties " with the veins, or occasionally in connection 
with faults of slight displacement. Vugs or cavities occurring within the actual veins, and often 
associated with bonanza ores, are not an uncommon feature in these mines. A specimen from one oi' 
these cavities shows (a) the wall-rock, a light-grey felsitic tuff or tufaceous mudstone, seamed with 
veinlets of bright pyrite ; (b) white crystalline quartz — this contains a considerable amount of gold 
in a very fine state of division, and is deposited directly on the wall-rock without any intervening selvage 
or parting (" frozen on," to use the expressive phrase of the miner) ; (c) an irregular band of crystallized 
quartz showing no gold — each of the transversely set quartz prisms is terminated by pyramidal faces ; 
(d) calcite containing no gold — this is deposited as large rhombohedral crystals on the comby quartz. 

The order of mineral -deposition in this specimen is evident, as is also the effect of the wall-rock 
in the precipitation of the gold. Other specimens, however, do not show this crustification, and the 
quartz and calcite are often irregularly associated. The gold, while in the main associated with the 
quartz and pvrite, is sometimes visible as grains and threads in the cleavages of the calcite crystals. 

The " Tokatea," " Tribute," and the other known veins in the Royal Oak and Tokatea Claims, 
have been fairly well exploited above the present adit levels. The possibility, however, of highly auri- 
ferous vein-quartz still existing, even in tin- near vicinity of old workings, is frequently demonstrated. 
The discoverv of bonanza ore in Farmer's vein — a " dropper " or branch of the " Tribute " occurring 
below No. 5 level— has contributed most of the mine's gold-output of the last few years. This branch 
vein was, prior to this find, considered valueless, as the result of an insufficient amount of prospecting- 
work. The hardness of the country rock renders its penetration very expensive, and has thus prevented 
more extensive prospecting crosscuts being driven on those horizons in which the known veins have 
proved so highly payable. 

It will be observed by the plan of the mine (Map, page 122) that the workings do not extend so far 
eastward on the " Tribute " as on the " Tokatea " vein. In all the levels the workings on the " Tribute " 
terminate in this direction at the western wall of a hornblende porphyrite dyke, which crosses the 
vein nearly at right angles. This dyke is about 25 ft. in width, and dips to the eastward. The fact that 
fairlv hijdi-gTade ore has been recently found to exist in the " Tribute " vein to the east of the dyke 
should warrant further prospecting-work in this direction. 

Disappointing results have attended operations on the "Tokatea" and "Tribute" veins at the 
No. 7 level. The former vein has maintained its size, but those portions carrying payable ore are few 
and far-between ; the latter has been reduced to a mere mineralised crack, and carries no ore-values. 
It is stated that small patches of bonanza ore were mined from the " Tokatea " vein in the shaft-workings 
below the No. 7 level, but the gold won was not commensurate with the heavy expenses of pumping 
and winding. If further exploitation of the deeper levels of this property be attempted it will probably 
be by means of an adit level driven from the western slopes of the range. 

Harbour View and Pride of Tokatea Claims. — The Harbour View and Pride of Tokatea Claims, 
situated to the south of the Royal Oak Mine, have been worked on veins which are closely allied to 
those already described, and, like them, occur altogether on the foot -wall side of the " Big Reef." 

The main returns from the Harbour View Claim were obtained during the early days of the gold- 
field, and are not available. From the Pride of Tokatea, the Hauraki Associated Company and the 
former owners of the ground obtained, according to the statistics, during the period 1890-1900, gold 
and silver to the value of £11,118. The veins worked by the company were the " Rainbow Reef " 
and the " Foot-wall Leader," their characteristics and the enclosing rocks differing in no respect from 
those of the Royal Oak Mine. 

West Tokatea Claim. — In the West Tokatea Claim work was confined to certain small veins oc- 
curring immediately to the south of the Tokatea Saddle, and on the foot-wall side of the " Big Reef." 
The rock carrying the veins is identical with certain varieties of that occurring in the Royal Oak, and 
porphyTite intrusions have been located. From the, veins, pockets of bonanza ore have been obtained, 
but these were of small extent and of infrequent occurrence. 

The company's battery consists of one rock-breaker, three light stamps, and two berdans. 



124 

Queen of the North (Monte Cristo) Claim. — The Queen of the North Claim is located near the crest 
of the range and to the north of the Royal Oak Mine. A gold-return of £1,999 is reported from the 
claim for the period 1887-1900. A much more extensive shoot of ore was mined in former years from 
the intersection of a rather large mineralised stratum (" mineral head ") with one of the veins. This 
" mineral head " is reported to be identical with one of the same " indicator bands " described as 
occurring in the Royal Oak Mine. 

(c.) The Veins of the Success Hill and Vicinity. 

Those veins of the Success Hill and vicinity which have proved of any commercial importance 
are, like those of the Tokatea Hill, situated on the foot-wall side of the " Big Reef." Patches of 
phenomenally rich ore have been obtained at different times from the various veins, but these deposits 
were of such small extent and infrequent occurrence that the claims have never yielded substantial 
returns to any of the prospecting companies. The gross returns obtained by the several companies — 
Success (Try Again), Southern Star, New Hauraki, and Karaka — that were operating in this special 
area during the years 1891-1901 only amounted, according to statistics, to £4,862. 

The principal veins are termed the " Jubilee " Nos. 1 and 2, " Success " Nos. 1 and 2, and James's 
" East and West Reef." The enclosing rock is a propylitised andesite, apparently of tufaceous nature. 
According to various reports certain of these veins in the upper levels of the Success Mine afforded 
some splendid examples of secondary enrichment. Sheets of " gold " (electrum) without any admix- 
ture of gangue-minerals were found enclosed in open cavities in the vein fissure. These were described 
to the writers " as hanging from the top of the cavity like leaves of a book," an occurrence which would 
indicate precipitation from descending solutions. 



WAIKOROMIKO SPECIAL AREA. 

The Waikoromiko special area is situated on the eastern side of the main range, and between the 
Waikoromiko and Kopurukaitai Streams. The principal claims are located in the bold spur which 
separates the valleys of the streams mentioned. These claims are styled the Four-in-Hand and the 
Tandem. 

The country rock consists of more or less propylitised andesites disposed with a dip to the east- 
ward. The main gold-bearing rock appears to be an altered hypersthene andesite, which is observed 
in the lowest level of the Four-in-Hand Mine to overlie the coarsely textured hornblende andesite ex- 
posed in the bed of the Waikoromiko Creek. 

The Four-in-Hand and Tandem Mining Claims. — The Four-in-Hand Mining Claim, now the property 
of private individuals, was until recently worked by an Auckland company, and has from the period 
1898 to 1906 obtained gold and silver to the value of £19,054. From this production dividends to the 
amount of £4,500 were paid. 

The property has been exploited from four main adits driven from the Kopurukaitai side of the 
spur. A low-level crosscut driven from the Waikoromiko side was abandoned after some 875 ft. of 
driving had been accomplished. A further 180 ft. of driving is required to intersect the principal vein 
at its calculated position. 

The most important vein of the claim is the Four-in-Hand, and with it are associated a foot-wall 
and hanging-wall branch. Other veins, among them the Tainui, traverse the property, but have received 
little attention. The whole vein-system has a general north-south strike, therein coinciding approxi- 
mately with the trend of the main spur. The prevailing dip is to the westerly. 

The Four-in-Hand vein where exploited ranged in thickness from a few inches up to 4 ft., the gold 
occurring in the quartz-pvrite gangue either as shoots or as a rather more general dissemination than 
is usual in the Coromandel veins. The much smaller hanging-wall branch afforded a considerable 
amount of rich bonanza ore, and where coming in contact, in its serpentine course, with the parent vein 
gave rise to a marked enrichment of the larger mass of vein-material. This in conjunction with other 



PLATE XXXI. 




New Four-in-Hand Company's Battery, Waikoromiko. 




Royal Oak Battery," Tokatea Hill. 

[Photo, by W. Beattie and Co., Auckland. 



Geo. Bull. A r o. I,.] 



[To face p. 125. 



Per ' 
Dwt 




Ion. 
21 


o 


12 


Dwt, 
2 


gr. 
5 


23 



125 

facts would suggest rock-fracture and mineralisation at two different periods, the formation of the 
younger vein being coeval with enrichment of the older. 

The Tandem Claim, held by private individuals, is located on the strike of the Kour-in-Hand vein- 
system, but the state of the workings did not permit of its examination. 

It would appear, from surface indications and from the general character of the rock forming the 
main spur, that further discoveries in the Waikoromiko special area may be anticipated on the trend 
of the vein-svstem both to the north and south of the Four-in-Hand Mine. Even in the existing claims 
the present state of mining activity appears to be largely attributable to the fait that no provision 
was made for prospecting-crosscuts at a time when the ore-shoots located were affording substantial 
returns. 

The valley of the small headwater branch of the Kopurukaitai marked d on the general map. should 
warrant prospecting in view of the detrital gold in this stream -debris. Two small veins occurring at 
the head of this stream gave gold by crushing and panning, although the assay-result of samples taken 
were disappointing. The small vein exposed in the large slip at the head of this stream yielded : — 

Gold 

Silver 

The vein some 10 chains lower down stream and on its left hank assayed : — 

Gold 
Silver 

Value, 9s, per. ton. 



THK OLD WHANGAPOUA MINIM; CLAIM (LlLLIs). 

This claim is situated on the upper eastern slopes of the Success portion of the main range 
within the Waikoromiko Valley, and is apparently on the auriferous belt extending from Preece's 
Point to the Four-in-Hand Mine (Kopurukaitai). 

This claim, worked under the above titles, has produced during the period 1890 to 1904 gold to the 
value of £6,450. The principal vein ranges from 2 in. to '1 ft. (5 in. in width, and is associated with 
propylitic andesites. The payable ore occurred in the upper levels as rich " pockets." Some of the 
gold obtained years ago resembled a loosely compressed mass of thread-like metal turnings. The 
amount obtained on one occasion would fill a couple of ore-bags, and was melted without any prepare 
battery treatment. This form of gold was evidently mined from close to the surface, as a small amount 
of dark-brown loam was entangled with the filaments. The precipitation of gold from aqueous solutions 
by organic matter may probably account for this peculiar deposit. 



PRKKCK S POINT SPECIAL AKKA. 

Preece's Point is the small but conspicuous peninsular ridge jutting out from the central portion 
of the eastern shore-line of the Coromandel Harbour. The maximum elevation of this bare or lightly 
wooded ridge is about 350 ft. 

The country rock consists of the volcanics of the " First Period " — andesitic tuffs, and to lesser 
extent lava-flows mostly in a state of advanced propylitic alteration. 

Several veins, as Map (page 104) will indicate, have been located in this area. These veins varv up 
to a foot in width, have a general north-and-south strike, and would appear to be genetically related 
to those of the Hauraki special area, situated about a mile to the northward. The results that have 
attended the limited amount of prospecting-work have proved unremunerative, although small prospects 
of wonderfully rich ore have at times been encountered. 



126 

Certain veins outcropping below high-water mark on the northern shore of the area have been 
shown to carry ore of somewhat low grade, in which the gold appears to be more evenly disseminated 
than is usual in the Coromandel veins. The heavy expense for drainage caused the insufficiently capi- 
talised svndicates or companies to prematurely abandon the prospecting operations undertaken from 
shafts sunk on these veins. 

A general sample for assay taken from " Bremner's reef " yielded on assay : — 

Per Ton. 
Dwt. gr. 

Gold .. .. .. .. .. .. .. ..3 3 

Silver .. .. .. .. .. .. .. . . 1 14 

Value, 12s. 8d. per ton. 



THE " PROSPECTS OF LITTLE PAUL S CREEK VALLEY. 

Perhaps no creek in the Coromandel subdivision is better known to the mining prospector than 
Little Paul's Creek, the main southerly branch of the Whaiwango, flowing into Koputaualri Bay. 
In the early days of the goldfield considerable quantities of highly auriferous vein- quartz were dis- 
covered in the debris of this stream. A great amount of prospecting has been carried out, but no 
vein carrying ore which is considered to correspond with these valuable erratics has ever been dis- 
covered. 

Owing to the existence of an inlier of much indurated strata of the Tokatea Hill Series, at and near 
the junction of Little Paul's Creek with the Whaiwango, the stream has, in the soft propylitic andesites 
above this point, reached a false base-level of erosion. Alluvial terraces and gravel debris conceal 
much of the bed-rock of the valley, hence prospecting operations are rendered both difficult and ex- 
pensive. Little or no detrital gold is now being delivered to the creek, so it would appear that the 
caps of the auriferous veins are not at the present time exposed to weathering action, but are covered 
by surface debris. Carbonaceous bands occur in the andesitic tuffs in the vicinity where the Coro- 
mandel - Cabbage Bay Boad crosses the creek-valley. These are highly pyritised and silicified, and 
should, as in the Kapanga Mine, have a favourable influence on the value of any veins found to inter- 
sect them. 

Between this road and the crest of the range is situated the Triumph mining area (old " Three 
Brothers "), the veins of which have yielded several patches of highly auriferous quartz. This quartz, 
it is stated, was not of the same character as the detrital ore of the lower part of Paul's Creek. An 
examination of both Little Paul's Creek and the Triumph area shows that there is still ample scope 
here for further prospecting. 



THE VEINS AND MINERALISED RHYOLITES OF AITKEN, PETOTE, AND TIKI CREEKS. 

The Veins. — In Aitken and Petote Creeks, branches of the Karaka, and in Tiki Creek, a branch 
of the Waiau River, certain veins occur at or near the contact of the andesites and the basement 
sedimentaries. These veins are characterized by containing in general a greater percentage of mixed 
metallic sulphides than those associated with the andesites ; furthermore, they have never been 
found to carry gold in payable quantities. 

In Aitken Creek and the spur between this and Petote Creek a vein and branch vein, varying from 
a few inches to 2 ft. in width, have been worked by the Aitken's Freehold and Empress Companies, 
but without success. In Petote Creek the vein which has received most attention is known as the 
" Galena Lode," and occurs in the indurated argillites just below the high falls (145 ft.) in the water- 
course. From what could be observed in the old workings, the vein, which ranges in width from almost 
zero to 12 in., has a course of north 12° west, with a dip to the westward at high angles. The vein- 
material is disposed as lenses, which give out along the strike (and probably dip) and are succeeded 
by similar lenses. These sheets consist either of quartz containing a fairly high percentage of galena, 
blende, pyrite, and chalcopyrite, or of quartz containing only a very sparse dissemination of these sul- 



127 

phides. The galena is argentiferous to a small extent, but gold is absent or present only in very small 

quantity . 

Concerning this vein, Maclaren, who examined it when prospecting operations were in progress, 

remarks, " On assaying a bulk sample I obtained the following ore-content : — 

Quantity per Ton. 
- Metal - Oz. dwt. 

Silver .. .. .. .. .. .. .. . . 2 14 

Gold 1 

Lead .. .. .. .. .. .. .. .. 16"8 per cent. 

Copper . . . . . . . . . . . . . . . . 4 per cent. 

Given a sufficient quantity of ore, and with efficient concentration, the above lode should yield a hand- 
some profit on outlay. The quantity can, however, only be determined by prospecting-drives."* 

The writers have noticed from a printed prospectus recently circulated that the gold-content of 
this vein is considered to be much higher than that determined by Maclaren. A sample of this sulphide 
ore collected from the mine " paddock " was therefore submitted to the Colonial Analyst for gold-silver 

assay. The report is as follows : — 

Per Ton. 
Oz. dwt. gr. 

Gold .. .. .. .. .. .. .. .. 14 

Silver .. .. .. .. .. .. ..188 

The prospecting operations undertaken since Maclaren's report was written have failed to show that 
the vein contains the ore in payable quantities : further attempts to prospect this and other veins 
are, however, contemplated. 

Another vein, or a further outcrop of the one already described, is exposed in an open cut some 
7 chains further up the creek. The actual vein-material here measures 6 in. in width, while the wall- 
rock on its hanging-wall side is sparsely impregnated with sulphides for a distance of 2 ft. 

Two distinct bands constitute the vein proper — one. 2 in. to 3 in. in width, consisting of nisty 
quartz, the other, 3 in. to 5 in. in width, of quartz high in chalcopyrite and its alteration-products. 
The following is the result of an analysis of the rusty quartz : — 

Per Ton. 
Dwt. gr. 
Gold .. .. .. .. .. .. .. .. Nil. 

Silver .. .. .. .. .. .. .. . . 7 13 

An analysis of the quartz-chakopyrite ore resulted as follows : — 

Per Ton. 
Oz. dwt. gr. 
Gold .. .. .. .. .. .. .. .. Nil. 

Silver .. .. .. .. .. .. .. . . 1 2 16 

Copper . . . . . . . . . . . . . . 1378 per cent. 

The vein, on account of its copper- content, warrants further prospecting at this point. 

In the right branch of Tiki Creek there are indications of the existence of veins similar to those 
of Petote Creek. At an elevation of 300 ft. (site of old dam) and a distance of 35 chains north of the 
main junction, a small galena seam about 1 in. wide is seen in the argillites of the creek-bed. Seven 
chains further north, and on the east side of the creek, a vein striking north 23° west has been located 
and drifted on some distance. It varies from 2 ft. to 3 ft. in width, and consists of quartz carrying 
a very small percentage of pvrite, galena, and chalcopyrite. Analysis for gold and silver yielded, — 

Per Ton. 
Oz. dwt. gr. 

|0 15 

Gold .. .. .. .. .. .. .. .. to 

(0 18 
4 2 

Silver . . . . . . . . . . . . . . ..J to 

(o 18 7 

* C.-9, 1900, p. 9. 



128 

Mineralised Rhyolites. — It has been stated in connection with the Pre-Jurassic stratified rocks 
that contemporaneous bands of rhvolite occur in association with the sedimentaries of the Tokatea 
Hill Series. 

In the Tiki and Petote Creeks these rhyolites are highly silicified, and, as the result of the decom- 
position of pyrite, are impregnated with iron-oxides. As it appeared probable that gold and silver 
might have been introduced with these secondary minerals, general samples of the rock were taken 
for analysis. The results, which are as follows, indicate, unfortunately, that these rock-masses have 

no economic value as ores. 

Per Ton. 



Analysis of silicified rhvolite from — Dwt. gr. Dwt. gr. 

Tiki Creek . . . . . . . . . . . . Nil 2 2 

Petote Creek . . . . . . . . . . . . 14 8 

Value of sample from Petote Creek, 2s. 4d. per ton. 



VEINS OF TIKI HILL AND MATAWAI VALLEY. 

The Tiki Hill and Matawai Valley have from time to time, since the early days of the goldfield, 
been the scene of active prospecting and mining operations. Limited patches of rich bonanza ore were 
obtained by the early prospectors, but the results attending the more extensive operations of the 
several companies were rather disappointing. During the period 1887-1906 the recorded value of 
the gold obtained only amounted to £3,829, and probably £20,000 would cover the total output since 
the opening of the field. The area is at present almost abandoned, and, owing to the collapsed state 
of the old workings, it is impossible to even map the positions of the veins. 

In Blackmore's old claim on the Tiki Hill, between the Pukewhau and Opitonui Saddles, the veins 
appear to have been associated with the altered interstratified rhyolites of the Tokatea Hill Series, 
but probably extended into the overlying andesites. From the Mines Report of 1887 it would appear 
that the vein in the adit entering the hill from the level of the Coromandel-Opitonui Road (that is, 
in the rhyolites) was about 18 in. thick, but carried little or no payable quartz ; it is likely, therefore, 
that the bonanza ore occurred in the vein at the higher levels where associated with andesites. 

In the Pukewhau Claim, on the upper slope of the hill overlooking Pukewhau Creek, only a limited 
amount of andesite overlies the sedimentary rocks, the lowest adit being driven near the contact of the 
two formations. In this adit the small vein, which had yielded pockets of very highly auriferous quartz 
in the upper levels, was unpayable. 

In what is probably the old Golden Belt Claim, adits penetrate the altered grits of the Manaia Hill 
Series, but whether or no payable returns were obtained here could not be ascertained. 

It would appear therefore that mining on the Tiki Hill has been connected with three distinct rock- 
formations — namely, the Tokatea Hill Series, the Manaia Hill Series, and the " First Period " ande- 
sites. It is, however, fairly safe to assert that the veins in the andesites have yielded the greater bulk 
of the gold. 

Mention should here be made of a large quartz vein which occurs at an elevation of 730 ft. on the 
ridge traversed by the Tiki-Opitonui Road, and lying between the Pukewhau and Matawai Valleys. 
This vein is associated with argillites, and is not far distant from an intrusion of porphyrite. Its strike 
is probably about north-south, and its width may exceed 10 ft. or 15 ft. The finely crushed quartz, 
which contains a little pyrite, yields, on carefully "panning off," a small amount of gold in a finely 
divided state. Only a limited amount of work has been done on the vein, and further prospecting on 
its southerly extension in Endean's Mining Freehold, where the country falls steeply, would seem 
advisable. 

Within the Matawai Valley the most productive veins yet discovered occur on the southern slopes, 
about a mile and a half from the stream's junction with the Waiau River. These veins are included 
within the old claim known as Vizard's and Vaughan's (Matawai). The latter claim, worked during 
the years 1887 to 1903 under the title of the " Castle Rock," produced gold and silver to the value of 
£2,770. 



129 

The country rock of the Castle Rock Claim consists of propylitic andesite, overlying an old highly 
inclined surface of the Manaia Hill grits and argillites. In the workings from the lowest adit the prin- 
cipal vein ranges from 2 in. to 1 ft. in width, and is associated with the andesites. In addition to 
pyrite, arsenopyrite and a small amount of stibnite occurred throughout the quartz ; the ore had there- 
fore to be calcined in order to extract the gold by the amalgamation process. A smaller branch vein 
was observed in the workings, occurring at the contact of the andesites and argillites, but this apparently 
yielded no payable ore. 

In Vizard's Claim none of the workings admitted of examination, but the vein- material bears the 
same character as that of the Castle Rock. 

All the highly auriferous quartz from these two claims was evidently mined from the upper por- 
tions of the veins, where they are associated with the andesitic rock. 



PROSPECTS OF MANAIA VALLEY. 

Within the Manaia Valley the prospecting and mining operations of the past have not been 

attended with remunerative results, although small patches of "specimen stone" have been 
occasionally unearthed. Most of this highly auriferous ore has been derived from the small veins of 
the Victoria or Golden Hill Claim, which lies immediately to the south of the subdivision. 

A- it Tiki Hil 1 . three distinct rock-formations — Tokatea Hill Series, Manaia Hill Series, and the 
" First Period " andesites are involved in the structure of the Manaia area. While gold has been found 

in the debris of streams incising each class "t rock, payably auriferous veins have never been located. 

In Taurarahi Creek the alluvium affords more gold on washing than does that of anv other creek 
in the subdivision. Much of this gold exists as heavy particles. Since no quartz veins were detected 
in the course of the creek, nor do quartz fragments occur in the debris to anv considerable extent, it 
would appear that some, if not all. of the detntal gold has been derived from joint-planes in the grits 
and argillites. These joints are tilled with iron-oxides, and have been proved to contain more or less 
gold. The latter metal may have been originally introduced m a pyritic matrix, or has either gravi- 
tated or descended m solution during weathering processes from higher levels. The old Leading 

Wind Company would appear to have exploited "irony" seams of this nature, with results which 
inevitably proved unremunerative. Near the headwaters ot the Taurarahi. and extending to the Maha- 
kirau divide, a belt of propylitic andesite- exists, which mighl be expected to afford, on prospecting, 
better results than the lower part of the valley. 

In the two main branches of the Manaia the area mapped as Tokatea Hill Series affords the light - 
grey spotted tuffs and tufaceous mudstones so characteristic of the Royal Oak and other mines of the 
Tokatea. Quartz veins do not appear in these rocks in the exposures afforded by the creeks, nor do 
the rocks, although highly pyritised, show pyritic bands such as are usually associated with the highly 
auriferous quartz veins of Tokatea. It cannot be affirmed, however, that the Manaia Valley has been 
systematically prospected, and there appears to be no reason why further discoveries should not be 
made. 



VKINS OF OPITONUI VALLKY. 

The Opitonui special area is situated within the valley of the Opitonui Stream (Whangapoua). 
The country, which in the vicinity of the vein has little local relief, consists of more or less 
propylitised andesites referable to the " First Period." Associated with these volcanic rocks in the 
Maiden Mine, a hornblende porphyrite has been detected, thus suggesting the presence of intrusives. 

Prospecting and mining operations on this particular area date from the year 1890, but the total 
value of the output recorded up to 1893 is only £1,025. In 1899-1903 the operations of the Kauri 
Freehold Gold Estates (Limited) were mainly centred in this locality (see p<w Hi), ore to the amount 
of 53,355 tons being mined and milled for a gold-silver return valued at £63,723, 
9— Coromandel. 



130 

The principal veins worked here were designated the Maiden. Carvill. and Hilda ; others of lesser 
importance being the Opitonui, Zealandia, Australasia, and Cross Reef. The three first-named veins 
show strikes not far removed from east and west, but the Opitonui — a large vein — and certain others 
more nearly approach the meridional direction. Only scanty information is available as regards the 
vein-characteristics or underground conditions. The most productive vein — the Maiden — ranged 
from 2 ft. to 14 ft. in width, with an average of about 6 ft. In the lowest mine-level the vein, which 
in the softer propylitic rock preserved the average width quoted, contracted immediately to about a 
foot on intersecting a " hard bar." The latter is probably the dyke which has afforded the specimen 
of hornblende porphyrite collected by McKay from the " tip-head." If so, the intrusions are ' evidently 
of greater antiquity than the veins. 

The gold and silver, alloyed in about equal proportions, occurred fairly evenly disseminated through- 
out the ore and also in a state of greater concentration in certain thin partings in the vein. 

The Opitonui vein, which is from 10 ft. to 12 ft. in width, outcrops conspicuously on the left-hand 
branch of the Opitonui Stream at a low elevation. Its northerly continuation would appear to form 
the quartz " blow " appearing some few chains south of Lanigan's shaft. The vein-material as exposed 
consists of white crystalline quartz showing partings stained with oxide of manganese. The sample 
taken> for analysis gave negative results^for^gold^and silver, but trial crushings taken from certain 
points are said to have proved the vein-material to be auriferous, though not payably so. 



VEINS OF THE MAHAKIRAU VALLEY. 

The valley of the Mahakirau above the junction of the Waitakatanga Creek includes two areas, 
which are more or less auriferous. 

One of these is included within a belt of propylitic andesites, about 60 chains wide, extending 
from the headwaters of Battery and Waiparu Creeks on the south side of the main valley, into the 
watershed of the Day Dawn and other small creeks on the north side of the valley. The other belt, 
a mile and a half further westward, includes the watershed of Jubilee Creek and extends westward 
and south-westward to the main river, which here flows in a northerly direction. 

Veins of Battery and Day Dawn Creeks. — In Battery Creek, at a point about 45 chains from the 

main river, there is exposed a quartz vein 20 ft. in width striking north 30° east. On its southerly 

extension it forms the conspicuous " quartz blows " on the ridge between this small creek and Mclsaacs 

Creek. The quartz contains pyrite and a small percentage of antimonite. No gold could be detected 

on crushing and panning, while the sample submitted for analysis returned only — 

Per Ton. 
Dwt. gr. 

Silver .. .. .. . . 2 13 

Some work appears to have been done on this large vein, but with what results could not be ascer- 
tained. A nearly parallel vein 12 in. in width, which appears from the " dump " to have been drifted 
on for a long distance, is exposed at a point 4 chains further up the creek. No '' prospect " could be 
obtained by crushing and washing the vein- material. 

A third vein, showing a width of 6 ft., occurs 20 chains from the mouth of this creek. It stands 
above the soft decomposed andesite as a strong rib striking north-south, and is followed by the creek 
for some distance. Pyrite and antimonite are conspicuous in the vein-material, but concentration- 
tests showed no gold. 

An analysis yielded — Per Ton. 

Dwt. gr. 

Gold .. .. .. .. .. .. ..0 7 

Silver .. .. .. .. .. .. .. . . 22 

From the " prospects " of gold contained in the debris of Battery Creek nearer its mouth, it would 
appear that an auriferous vein not yet located exists lower down the creek -valley than the veins just 
described. 



131 

To the north of the Mahakirau River a vein known as the Day Dawn has been located on the 
small spur lying to the west of the Day Dawn Creek. This vein, which strikes north 27° east, and 
dips to the north-west at an angle of 65°, ranges from 4 in. to 2 ft. 6 in. in width. The lode-matter is 
poorly demarcated from the wall-rock. It consists principally of quartz, oxides of iron and manganese, 
and yellow clayey material. (Jold is occasionally visible in the ore, and it is stated that the trial crush- 
ings gave returns which would show a margin of profit provided more systematic methods of mining 
and crushing were adopted. 

A sample of the vein-material taken from the only accessible part of the western adit yielded on 

analysis — 

Per Ton. 
Dwt. gr. 

Gold .. .. 3 10 

Silver .. .. .. .. .. .. .. 1 14 

Value, 13s. lOd. per ton. 

Mention shou'd here be made of a patch of " specimen stone " reported to have been discovered 
in landslip-debris on a terrace of the southern bank of the Mahakirau River, midway between the 
mouths of Battery and Day Dawn Creeks. The many small adits observable in the vicinity of this 
terrace are evidences of futile attempts to locate the parent vein. An examination of the locality 
would suggest that this auriferous vein-quartz had its origin at a somewhat higher elevation than that 
of these adits and prospecting- pits. 

Veins of the Jubilee Creek and Vicinity.— In Jubilee Creek the most productive vein yet located 
occurs about 60 chains from the main river. (See map.) Although only 2 in. to 5 in. in width, the vein 
is well defined and has yielded a few small shoots of highly auriferous ore. Stratified andesitic tuff or 
ash-beds, highly propvlitised, constitute the enclosing rock. The last return reported was obtained 
in the year 1901, when 6 tons of ore yielded gold-silver bullion to the value of £348. 

A similar vein, upon which no work has been done, outcrops in the creek-bed about 35 chains 

nearer the river. A sample of the quartz gave on analysis — 

Per Ton. 
Dwt. LT. 

Gold . . . . . . . . 22 

Silver . . . . . . . . . . . . ..015 

On the spur to the westward of Jubilee Creek a vein of some 1' ft. in width has been recently located. 

Two samples forwarded to the writers were analysed, with the following result : — 

Per Ton. 
(!•) Oz. dwt. .1. 

Gold .. .. .. .. .. .. .. ..016 

Silver .. .. .. .. .. .. 2 15 11 

Value lis. 6d. per ton. 

(2.) 

Gold .. .. .. .. .. .. 15 

Silver . . . . . . 1 10 21 

Value, 6s. 3d. per ton for gold and silver. 
Antimony was present in this ore to the extent of 966 per cent. 



VEINS OF MATERANGI, MURPHY S HILL, OWKR\, AND MOEWAI. 

A fairly well-marked line of mineralisation is that extending from Materangi Ridge, near the 
northern coast-line of the Kuaotunu Peninsula, through Murphy's Hill and the Owera Valley to 
the Moewai Claim, situated near the head of the Ngarahutunoa Creek, flowing into Mercury Bay. 

The rocks of this belt are fragmental and massive andesites and dacites of the " Second Period," 
considerably propylitised and weathered. This weathered rock presents a rather coarse texture and a 
characteristic purplish-grey colour. 
9* — Coromandel, 



182 

The veins, on account of the somewhat sinterv and occasionally platy character of the quartz 
and the fairly uniform dissemination of the gold-silver content throughout the ore, resembled the 
Kuaotunu rather than the Ooromandel veins. The very high-grade ore characteristic o c +he last- 
named locality has never been found in the mines located on this belt, nor have any of the mines it 
may be remarked, yet yielded remunerative returns to the owners. 

Materangi Ridge Veins: The principal vein of the now abandoned Wild Wave and Ocean Mew 
Claims traverses nearly longitudinally the Materangi Ridge. It strikes north 10° west, dips at high 
angles to the westward, and ranges from a few inches to 3 ft. in width. The vein-material consists of 
a loose mass of quartz, silicified rock, and clayey material, stained with iron and occasionally manganese 
oxides, and is not sharply demarcated from the wall-rock. A general sample taken from the vein 
in those parts of the old workings still accessible gave on analysis — 

Per Ton. 
Dwt. gr. 

Gold .. .. .. .. .. .. .. 6 22 

Silver .. .. .. .. .. .. .. ..3 4 

Value, £1 8s. per ton. 

Statistics show that 34 tons of ore was crushed from the Ocean View Claim during the period 1892-93, 

for a return valued at £200. 

Murphy's Hill Veins : At Murphy's Hill the principal vein presents similar characteristics to that 
of Materangi, except that sinterv white quartz and the oxides of manganese are here more abundant. 
The vein, which is exposed both on the north-east and southerly flanks of the hill, strikes north 45° 
east, and dips to the south-east. Its width, from what can be observed in the old workings, appears 
to average about 3 ft. 

A general sample of the vein-material, broken from the reef on the north-east side of the hill, 
yielded on analysis — 

Per Ton. 
Dwt. OT. 

Gold .. .. .. .. .. .. .. ..0 7 

Silver . . . . . . ... . . . . . . . . 23 

From the old mine-workings of the southerlv flank of the hill — 

Per Ton. 

Dwt. gr. 

Gold .. .. .. .. .. .. .. .. 1 13 

Silver .. .. .. .. .. .. .. . . 23 

A crushing of 4 tons of ore from Murphy's Hill during the period 1891-95 yielded 48 oz. 1 dwt. of 
bullion, valued at £105 12s. 

Owera Veins : In the Owera Claim, situated on the spur lying between branches of the Owera 
and Otanguru Creeks, mining operations rather more extensive than at the two localities just described 
have been carried out. The proprietary company erected a 10-head stamp-battery in the vicinity, 
and during the period 1890-95 mined and crushed 1,786 tons of ore for a return of 2,207 oz., valued at 
£3,806. 

Collapse of the entrances to the several adits precluded examination of imderground conditions. 
The principal vein — the Owera— has a strike of north 30° east, and a dip at high angles to the east- 
ward, with a width averaging 2 ft. In addition to the brownish oxidized sinterv quartz pitted with 
drusy cavities, the white friable laminated variety, characteristic of Kuaotunu, is occasionally visible. 

Several outcrops of vein-material have recently been located by prospectors on the Otanguru 
slope of the spur. General samples from these occurrences showed on analysis a gold-content varying 
from 22 gr. to 1 oz. 16 dwt. per ton, and silver 1 dwt. 22 gr. to 2 oz. 3 dwt. 12 gr. per ton. Since the 
exposures are in the near vicinity of, and at a higher elevation than, the deepest of the old workings, 
they may only be the outcropping portions of the Owera vein, already worked. A reopening of the old 
adits can alone prove their commercial value. 

The Moewai Claim : The principal vein of the Moewai Claim — Ngarahutunoa Valley — closely 
resembles in the character of its ore the Owera and Materangi veins. Its course is north 20° east, dip 
is to the eastward at high angles, and width averages from 3 ft. to 4 ft. The ore is of low grade, although 



To CLCCvmpmy Bulletin. N?4< 




By Authority : John Markay, Government Printer, Wellington. 



133 

gold is occasionally visible in the solid quartz or in association with the iron-oxides. The steepness 
of the country gives facilities for cheap mining. The proprietors of the claim, being of opinion that 
the ore of the upper levels will leave a margin of profit, have a small stamper-battery in course of 
erection. 

VEINS AND MINING CLAIMS OF THE KUAOTUNU SPECIAL AREA. 

Locality and General Features. 
The Kuaotunu special area includes the watershed of the Kuaotunu Stream, and has further 
extension to the eastern slopes of the Waitaia Ridge, and to the southern slopes of the hilly country 
overlooking Mercury Bay. With the exception of the floor of the middle and lower parts of the 
river-valley the area is decidedly hilly, and in the south-eastern portion steep and rugged. The 
bold north-south-trending Waitaia Ridge, terminating near the northern coast-line in Black Jack- 
Hill, forms the eastern part of the area. About a mile to the westward, anil nearly parallel to this 
ridge, the Bald Spur is a conspicuous feature, jutting northward from the Kuaotunu Range and 
terminating in the valley between the two main branches of the Kuaotunu Stream. 

Geological Formation 

As the general map will show, the prevailing rocks of the area arc those ol the Manaia 
Hill Series (Jurassic). They consist here of fine conglomerates, gritty grauwackes, and argillites, 
considerably altered in the vicinity of the veins by hydrothernial agencies. In the small 
creek west of Hosie's Saddle, anil within the boundaries of the Waitaia Mimng Claim, there is exposed 
a sma'l patch of spotted tufaceous mudstones, which has been referred to the Tokatea Hil Series. 
This rock is identical with much of that occurring in the Royal Oak Mine (Tokatea). The Kuaotunu 
.ire. i of sedimentary rocks is on three sides Hanked and overlain by the andesites of the Beeson's Island 
Series. Special mention should here he made of a small tongue of andeaite which, extending north- 
ward from the main mass of the volcanics, forms the capping of the Bald Spur within the Kapai- 
Vermont Mining ( l a j m . 

In connection with rock-alteration, reference has beenpaade (see page MM) to the marked resem- 
blance which the altered grits of the Kuaotunu area bear 1<> propylitic andesites. On this account the 
contact of the andesites and the sediinentaries, in the mine-workings ol the Kapai-Vcrmont Claim, was 
evidently not recognised by those connected with the mining operations. 

The Veins and Mining Claw 
Two principal areas of mineralisation are recognisable on the Kuaotunu Goldheld —(a) thai of 

the Bald Spur, enclosing the "Try Fluke"' and allied veins; (b) that of the Waitaia Ridge, enclosing 
the veins of the Waitaia and other claims. 

With the exception of the minor capping of andeaite on the south end of the Bald Spur, the rocks 
enclosing the veins are the gritty grauwackes or argillites. In no other part of the subdivision have 
payably auriferous veins been shown to exist in the rocks of the .Manaia Hill Series. Furthermore, it 
will he noted from the following description that the character both of the gangue-imiierals and the gold- 
silver content distinguishes the veins of Kuaotunu from those of the mam Coromandel centre. 

The total gold-silver returns of the Kuaotunu Ooldfield, from its discovery (1889) to the 31s*i De- 
cember. 1906, according to the official reports amount to 82,756 oz., valued at £190,795, the amount 
of ore treated being 95,865 long tons. 

Veins of the Bald Spur and Vicinity. 
The principal vein of the Bald Spur, and the one which yielded the greater part of the 
gold of the Kuaotunu area, is known as the " Try Fluke." Its course is north 22° cast, 
and its dip is south-east at high angles. Professor Park, who examined the vein while 
mining operations were in progress, says : " It varies from 2 ft. to 12 ft. in width, and generally 
consists of friable crystalline quartz, often stained a black colour by manganese-oxides. In the more 
solid parts the lode-matter consists of flaky masses of quartz, made up of numerous thin leaves or 
lamina: of quartz often enclosing hollow rhombohedrons or triangles, which appear to be pseudomorphs 
after calcite. The laminae arc often as thin as a knife-blade, and, although closely packed like the 



134 



leaves of a book, do not touch each other, being separated by a space the thickness of a sheet of paper. 
Tttey appear to have formed along the cleavage-planes of calcite crystals."* Probably owing either to a 
crush effected by later movements of the wall-rock, or to a subsequent leaching-out of calcite deposited 
in intimate association with the quartz, much of the vein-material in the Try Fluke Mine is stated 
to have resembled " a mass of gritty sand." The tendency of this material to " run " necessitated 
special precautions being taken in stoping operations. 

Every mining report on Kuaotunu makes reference to the exceedingly fine state of division in 
which the gold-silver electrum existed in the ore, and particularly in the ore of the Try Fluke vein. 
The percentage recovery of this fine gold by the ordinary amalgamation process as practised at Coro- 
mandel proved altogether unsatisfactory, and not until the introduction of a leaching process (cyanide) 
was the metallurgical problem afforded by these ores solved. The payably auriferous ore in the vein 
was disposed as a shoot of considerable width, pitching at a low angle to the southward. The richest 
portion in this shoot was at or near the vein's outcrop on the top of the spur (elevation, 650 ft.). Much 
of this gossanous ore, evidently the result of repeated natural concentrations, yielded over 15 oz. of 
gold per ton. Below this, in the Try Fluke Claim, ore of payable quality continued for some depth 
below the No. 4 level (270 ft. elevation). From this level, at a point 200 ft. north of where the Try 
Fmke vein crosses the Kapai-Vermont Claim boundary, a shaft was sunk to a depth of 100 ft. In the 
lower 10 ft. of this shaft a decided '' change of country " is stated to have been encountered, with a 
pronounced impoverishment and contraction in width of the vein. Below this break the rock is stated 
to be dark-coloured and soft, but in the opinion of the mine-managerf operations were prematurely 
abandoned owing to lack of capital. 

In the low level of the Great Mercury Mine, some 45 chains northward of the Try Fluke shaft, the 
vein has been intersected at an elevation of some 135 ft. above sea-level (that is, at an horizon 40 ft. 
lower than the workings from the Try Fluke shaft). Here again the vein, which intersects hard gritty 
grauwacke and argillite showing only a minor amount of alteration, is of small dimensions, and carries 
gold and silver to the extent of only a few grains per ton. In the upper levels of the Great Mercury 
the vein averaged 4 ft. to 5 ft. in width, afforded much high-grade ore, and was enclosed in a more 
highly altered phase of the same rock. 

To the east or hanging-wall side of the " Try Fluke Reef " occur veins known as the " Kuaotunu," 
"Red Mercury," and "Just-in-Time,' all of which have yielded a considerab'e amount of payably 
auriferous ore Other veins of the Bald Spur are those of the Otama and Handsworth Claims, which 
though small have afforded rich ore-shoots. 

The following tabulation, compiled from official reports, shows the results of mining operations 
on the several claims held from time to time on the Bald Spur : — 



Mine. 


Period of OperatioD. 


Quartz crushed 




Bullion obtained. 

Oz. dwt. 


Value 






Tons 


cwt 


Hi. 


£ s. d. 


Kapai 


1891-92 .. 




120 








103 





234 6 6 


Kapai-Vermont 


1893-98 . 






10,209 








12,079 


5 


29,028 18 2 


Try Fluke. 


1890-97 . 






35,565 








24,620 


5 


58,762 19 8 


John Bull 


1891-92 . 






105 








20 


2 


45 4 6 


Just-in-Time 


1890-95 . 






991 








1,009 


13 


2,275 19 9 


Carbine 


1889-92 . 






428 








956 


10 


2,152 2 6 


Mariposa 


1891-93 . 






680 








416 


4 


937 9 


Red Mercury 


1890-95 . 






4,556 








5,485 


16 


11,893 1 


Kuaotunu SyndicateJ 


1901-2 . 






2,215 








1,061 


15 


2,356 8 2 


New Mariposa§ 


1897-1903 




8,979 








4,273 


6 


9,679 7 8 


Al 


1896-97 .. 




28 








6 





14 


Great Mercury 


1889-1903 




20,373 


5 





14,502 


16 


29,755 x5 1 


Irene 


1891-1902 




3,087 








2,642 


9 


5,025 2 4 


Handsworth 


1896-1906 




393 


11 


48 


1,448 


11 


3,645 1 3 


Otama 


1889-1906 




310 


9 


40 


1,431 





3,255 6 


Juno 


1896-1902 




74 


2 


108 


708 


4 


1,647 7 


Totals 








88,114 


8 


84 


71,364 


16 


160,7<:8 3 1 



* " Geology and Veins of the Hauraki Goldfields," 1897, p. 100. t The late Mr John Goldsworthy. t Kuiotunu Syndicate 

claims are Mariposa and Kapai-Vermont. § New Mariposa included the Try Fluke, with its different sections, and the Kapai-Vermont. 



135 

Invicta Claim : The Invicta Mining Claim is distant some 30 chains from the Bald Spur, and is on the 
west side of the Kuaotunu Creek. The vein, which was worked in this claim at an elevation of about 
120 ft. above sea-level, is about 4 in. wide. Its course is north; 10° west, and its dip 60° to the west- 
ward. The workings have collapsed. A sample of the oxidized vein-material taken from the 

" paddock " yielded on analysis, — Per Ton. 

Oz. dwt. gr. 

Gold .*. . . . . . . . . . . . . . . 13 20 

Silver . . . . . . . . . . . . . . . . 2 2 20 

Value, £2 19s. 7d. per ton. 

During the period that mining operations were in progress 575 tons of ore were raised and treated, 
for a return of gold valued at £493. 

The Veins and Siliceous Sinters of the Waitaia Ridge. 

The Veins. — The principal veins of the Waitaia Ridge outcrop on its western slope about 
3ti chains to the south-west of Trigonometrical Station H. These are the ore-bodies of the Waitaia 
Mine. Minor veins also occur both to the north and south of this locality. 

Waitaia Mining Claim : The Waitaia Mining Claim, the property of the Waitaia Gold-mining 
Company, covers some 107 acres of the steep western slope of the ridge. The rocks consist entirely 
of altered sedimentaries. the disposition of which is not recognisable. Some half a mile to the north- 
east, however, the strata exhibit a north-south strike, with a dip to the westward. 

The principal vein is the Waitaia No. 3, while the No. 5, with its branch the " Blue Face," ranks 
next in importance. The No. 3 vein has a rather serpentine course averaging north 20° east. Its dip 
is irregular, varying from 72° to the eastward in the northern portion of the claim to 75° westward in 
the southern portion. All positions between those mentioned are encountered in this " warped " 
fissure. The vein, which is rather lenticular, ranges up to 10 ft. in width, and averages from 12 in. 
to 15 in. It is the result both of fissure-filling and of replacement of the wall-rock. Where best 
defined the vein-material consists mainly of white crystalline quartz, with bands or patches of dark 
bluish-grey quartz. Pvrite is abundant, particularly in darker bands and as thin films separating 
the darker- and lighter-coloured quartz. Arsenopvrite, galena, and blende are occasionally present in 
minor quantity. The gold, which occurs with silver in the average ratio of 100 : 39, is usually 
associated with the granular pyritc and pvritic films. What is locally termed " conglomerate " occurs 
comparatively frequently as the only vein-filling, and is of very low grade or non-auriferous. This is 
evidently a fissure-breccia — angular and rounded fragments of wall-rock cemented with a minor 
amount of siliceous material. The disposition of these breccia occurrences as "shoots" pitching at 
high angles, denotes vertical movement in a sinuous fault-fissure. 

The shoot of pay-ore in this vein has been followed to a depth of some 300 ft. below the outcrop. 
Including a few minor belts of non-payable " conglomeratic " and barren ore, the pay-shoot, which 
pitches southward at 45°, has a stope-length of 1,000 ft. Pockets of " specimen stone," ranging in 
gold-content up to " 3 oz. to the pound," are of occasional occurrence. A fault which effects a hori- 
zontal displacement of the vein of some 16 ft., in the northern end of the mine-workings, dips at high 
angles to the southward, and appears to limit the ore-shoot in this direction. 

The No. 5 vein, distant 130 ft. to the eastward, is nearly parallel in strike to the No. 3, and dips at 
high angles to the eastward. It has been intersected and drifted upon in the upper levels, showing 
an average width of 15 in. The rusty-coloured oxidized ore yielded battery-returns at the rate of £1 
per long ton. 

The company's mill, which is situated some 75 chains from the mine, consists of ten stamps, 
together with a poorly arranged cyanide plant and accessories, the motive power being steam. 

According to official statistics the Waitaia Gold- mining Company treated, during the period 
1891-1906, 5,848 tons of, -ore for a gold-silver return valued at £26,404. 

A low-level adit has been surveyed, which will intersect the veins at a depth of 160 ft. below the 
No. 5 level. The country rock exposed in the small creek rising in Hosie's Saddle, and at an elevation 



136 



of some 40 ft. above the proposed adit, closely resembles, as already stated, the rock' of the Royal Oak 

.Mine Tokatea. The phase of alteration exhibited by this rock, which will probably be penetrated 
in the low level, together with the results afforded by the vein at No. 5 level, are sufficient warranty 
for the contemplated expenditure in further development. 

Aorere Claim : In the Aorere Claim, lying immediately to the north of the Waitaia property, a 
continuation of what is probably the Waitaia No. 3 vein has been located. From the year 1893 to 1899, 
295 tons of ore were crushed for a return of £1,028. This was, it is said, mostly derived from a 
" chimney-like " ore-shoot of lenticular cross-section. 

Golden Anchor Claim : In the Golden Anchor Claim, to the east of the Waitaia, a vein 3 in. to 7 in. 
in width has been drifted on for some distance. A general sample selected yielded on assay only — 



Gold 
Silver 



Per Ton. 
( )z. dwt. gr. 

15 
15 



New Mint Claim : In the New Mint Claim, to the south of the Waitaia Mine and on the slope of 

the range overlooking Mercury Bay, a vein about 15 in. thick has been exposed. Its strike is north 

35° east, dip 65° westward, and width 15 in. This vein is evidently allied to the Waitaia veins, but 

the gold-content of the portion exposed is small. Analysis showed — 

I'er Ton. 
()z. dwt. gr. 

Gold .. .. .. .. .. .. .. ..016 

Silver .. .. .. .. .. .. .. ..016 

Other Claims : The following returns from various other Kuaotunu claims are submitted, to com- 
plete the recorded gold-silver returns from the field up to the end of the year 1906 : — 



Mine. 



Period of Operation. 



Quartz crushed. 



Bullion obtained. 



Value. 



Black Jack 
Bonanza . . 
Excelsior . . 
Kuaotunu 
Secret 
Venus 
Try Again 
Three Stars 
Loyalty . . 
Perseverance 
Victoria 
Lucky Hit 



1891-94 
1890-91 
1892-93 

1891-94 
1890-91 
2895-96 
1894-95 
1894-95 
1893-94 
1893-94 
1893-95 
1893-95 



215 


10 


10 





74 





507 





4 





96 





13 





12 





7 





31 





41 





22 






(Iz . 


dwt 


313 


1 


19 


(i 


31 





310 


5 


4 


6 


153 


1 


11 


12 


6 


2 


8 


5 


41 


11 


12 


10 



18 17 



Totals 



1,032 10 



929 10 



752 


6 


5 


rt.'t 


19 


8 


77 


10 





053 


1 


3 


9 








382 


15 





20 


2 


8 


14 


11 


5 


20 








97 


12 


6 


29 


7 


6 


44 


6 





2,162 


12 


5 



The Siliceous Sinters. — One of the most conspicuous features on the crest and flanks of the 
Waitaia Ridge are the white terraces and " shoadings " of siliceous sinter, the products of hot springs 
that formerly existed along its whole length. The most characteristic terrace formation occurs on the 
crest of the ridge at a point 50 chains south-east of Black Jack Hill, the accumulation being disposed as 
nearly horizontal layers. (See Plate 32.) The material, which is white or slaty-coloiired, and often 
vitreous, is in places of flinty nature, or again is finely crystalline. Layers showing porous or fibrous 
structure and stained with iron and manganese oxides are not uncommon. Four general samples 
were collected from various parts of these superficial deposits of sinter, but on analysis showed no 
traces of gold or silver. During the period of mining activity, adits were extended from the range- 
slopes under certain of these sinter cappings, in the hope that they might be connected with ore- 
bearing fissure- veins, but no veins of any description were encountered. 

Black Jack Hill, at the northern end of Waitaia Ridge, appears to have been the pipe of one of 
these old thermal springs. The sintery quartz and silicified grauwackes here contain a much higher 



PLATE XXXII. 




Siliceous Sinter Terrace <>n Waiiaia Ridge, Kuaotunu. 




Siliceous Sinter Terrace on Waiiaia Ridge, Kuaotunu. 

[Photo, by Mr. Alex. McKay, F.G.S. 



Geo. Bull. No. !,.} 



[To fare p. 136. 



Gold. 

Gr. 

3 


Silvi 
Qi 

5 


3 


12 


7 


8 


11 


i 


1 


14 


Nil. 


Nil. 



137 

percentage of iron and manganese oxides than do the superficial terrace deposits. A complete sampling 
of this material was undertaken at all points of exposure, and ten assay samples prepared : — 

2 samples yielded on analysis 

4 samples 

1 sample 

f sample 

1 sample 

1 sample 

The above results, though of scientific interest, show thai the deposit has no economic value as a 
gold-silver ore. 

VEINS OF WHACWHAU CREEK. 

The Whauwliau Creek, draining into Mercury Bay, incises the hilly country some two miles due 
south of the Kuaotunu Bald Spur. The rock consists altogether of "Second Period" andesites, 
propylitised and weathered. The locality is apparently on the southerly extension of the Kuaotunu 
general line of mineralisation. Intermediate between YVhauwhaii and Kuaotunu, highly pyritised 
propylitic andesites are found in the middle and upper course of Woodcock Creek. 

The only vein observed in these prospecting adits at the Whauwliau (see general map) strikes 
north-south, and ranges in size from a mere clay parting to a quartz-clay formation about a foot wide. 
The solid quartz, which resembles that of the Owera veins, contains very little gold. This metal exists 
only in the loose rusty clayey material, and as films on the walls of cavities in the quartz. Such vein- 
material is always of lower grade than it appears to be, and mining at Whauwliau has proved unre- 
munerative. , 

PCRANG1 SPECIAL AREA. 

The l'urangi rhvolitic area — that lying to the cast of the Wlntiaiiga Harbour— is markedly devoid 
of quartz veins. A fissure, or " pipe " deposit, of vitreous, chert v, siliceous sinter, of considerable 
dimensions, occurs in the valley of the small creek situated about half a nule to the west of Wigmore 
( 'reck. This deposit was stated to have afforded assays of 1 2 dwt. of gold per ton, but a general sample 
taken by the writers gave negative results for both gold and silver. A sample taken from a definite 
band carrying pyrite, arsenopyrite, and iron-oxides also yielded negative results. On the other hand, 
that gold docs occur in extremely small quantities in this deposit was shown by one or two minute 
" colours " having been obtained on panning off a dish of the oxidized disintegrated material. 

A siliceous-sinter terrace, from which a sample for assay was collected, occurs as a capping on a 
small hill 26 chains to the west of Trigonometrical Station l T . This material afforded no trace of gold 
or silver. 



138 



CHAPTER X. 



EXAMINATION OF FLUV1ATILE GRAVELS FOR THE LOCATION OF POSSIBLE 

MINERAL-BEARING AREAS. 



Introduction 

Results of Prospecting Operations — 
Colville and Moehau Survey Districts 
Harataunga Survey District 



Page 
138 

138 

139 



Page 
Results of Prospecting Operations — continued. 
Coromandel Survey District . . . . 141 

Otama Survey District . . . . 144 



Introduction. 

In the preceding chapters of this bulletin the nature, position, and extent of the main mineral-bearing 
areas occurring within the Coromandel subdivision have been described. The notes and tabulations 
of the present chapter are presented mainly with the intention of assisting the prospector in operating 
beyond the limits of the well-known mineral-bearing centres. 

In the traversing of the various watercourses, with the primary object of mapping the country 
both geologically and topographically, opportunity was afforded to carry on conjointly a preliminary 
prospecting for minerals of economic value. An expert mining prospector attached to each field party 
examined the debris of the banks and beds of the streams by the ordinary dish-concentration methods. 
While the possible occurrence in the concentrates of minerals other than gold was never overlooked, the 
problem over the greater portion of the area resolved itself into the determination of the presence or 
absence of the metal named. 

It may be here pointed out that the country examined gives no evidence of glaciation, with the 
attendant transference of rock-material from one watershed to another, such as obtains in many of the 
goldfields of the South Island of New Zealand. The determination of the presence of gold in the debris 
of the stream is therefore significant, and the deduction can almost with certainty be drawn that the 
metal has been derived within the confines of the stream-valley ; whether or no it occurs in payable 
quantity is, of course, quite another question. The negative evidence, however, as to the existence 
of gold as revealed by the rather rough dish-concentration methods, while in the main significant, cannot 
for obvious reasons be regarded as infallible. 

In order to economize space and to afford a more ready reference, the results are here presented in 
tabulated form, and an asterisk has been inserted where references have been made to a locahty else- 
where in this report. Branch creeks are referred to as right or left in the true sense — that is, according 
as they enter the main drainage-channel from the right or from the left of the observer, looking down 
the main valley ; the prospector is often accustomed to regard branch creeks in the opposite sense. 
Where several branch creeks occur they have been numbered to correspond with the numbers inserted 
on the plan. Creeks not mentioned in the following lists have not been specially prospected. 



Colville and Moehau Survey Districts. 

General Statement. — The streams of this area drain for the most part areas consisting of old sedi- 
mentary rocks, which in many cases are intersected by dykes and sheets of intrusive rocks. The veins 
which have been located, occur in close proximity to the intrusive rocks. The prospects of ore- 
deposits of economic importance being discovered in this locahty are certainly not encouraging. 



Mmtaan. 



Holland 
Stony Bay — 
Left branch 



Rieht branch. 



139 

Results of Prospecting Operations. 



Detrital Gold in Debria. 



Description. 



Povitton. 



Quartz Veins located. 



Description. 



Position. 



Enclosing Rock. 



Remarks. 



Bronlund 
Ohincwai 


Nil . 




Ongahi 
Sorry Ma.-y 






Hope 


A few 


' colours " 


VVaiaro 







Streams flowing to the \V< stern Coast-line. 

Little or no quartz. 

* Contains boulders of 
vu ggy quartz. (See 
page 109.) 

* See page L09. 
Small vein \ mile from Contact of * See assay, page 108. 

mouth ar,;illite and I 

porphyrite 



Vein pro- 1J miles from 
bably of mouth 

large size 



Streams flowing to the Eastern Coast-line. 



Nil 



Ditto . . * See assay, page 108. 



Little or no quartz in 
stream-debris. 



Quartz from vein not 
located ; said to occur 
on ridge. 
Argillite . . Old workings. 



Haratavnga Survey Distrk r. 

General Statement. — A glance at the maps accompanying the report will show the disposition ol 
the rocks forming the area Veins occur in the old grauwacke and argillites, and in the overlying 
Tertiary igneous rocks both of the " First " and " Second Periods." 

The propylitic andesites of the " First Per od " are the most favourable for the existence of metal- 
liferous veins, while the rocks of the Beeson's Island Scries ("Second Period"), which form coastal 
belts both on the eastern and western sides of the peninsula, appear to be singularly devoid of auriferous 
veins. 

The following results indicate that gold occurs in the debris of many of the drainage-channels. 
The auriferous veins which have already been located and worked by the prospector and m'ner have 
in no case returned sufficient go'd from the small " pockets " of rich ore encountered to cover the cost 
of its production, nevertheless the further prospecting of certain areas described in a previous chapter 
(page 109) would appear warranted. 



Results of Prospecting Operations. 



Str •am. 



Detrital Gold in Debris. 



Description. 



Position. 



Quartz VeinB located. 



Description. 



Position. 



Enclosing Rock 



Remark*. 



Kairauinati 



Streams flowing to the Western Coast-line. 

Small vein J- mile from Argillite 

mouth 
Quartz for- On ridge at Andesite 
mation head of 

stream 
Vein . . J £mile from „ 

mouth 



Old workings. 



140 



Results of Prospecting Operations — continued. 





Dotrital Golc 


in Debris. 


Quartz Veins located. 




scream. 








Rpmarkfl 




Description. 


Position. 


Description. 


Position. 


Enclosing Rock. 


x ic Li j cuas. 




Streams flowing 


to the Western Coast-line — continued. 




I'mangawha — 














Ngakuku > 

1 * 


a i 




Veins 6 in. 


Near head . . 




* See assays, page 110. 


- 1 




to 2 ft. 








1 & 


-5 _ 




wide 








* 

" St) 


Mi ~ 




Vein in. to 


At head 




* See assay, page 110. 


a 


-© ~ 

© 03 




1 ft. wide 








White Star | | 


O c 








.. 


* See reference to White 


i £ 


Id. 
rifer 










Star Mine, page 110 


Barney r*S 




2 in. vein 


Near junction 


Argillite 






o - 
be * 




Quartz for- 






Assay, 8 gr. gold, 15 gr. 


, '§ 


<*. s 




mation 






silver, per ton. 


»» 





o ^ 




in. vein 


1 mile above 


Contact of ar- 






£ 


5 _5 






junction 


gillite and 








S^ 








andesite 




Sutton 


§ J 




3 ft. vein 


J mile above 
junction 


Argillite 


Assay, 16 gr. gold, 16 gr 
silver, per ton. 


Anthony 


Nil . . 










Little or no quartz. 


Tawhetarangi . . 


s» ■ • 






•• 




,. 






Streams flowing to tin Eastern Coast-lint . 




Taylor 


Nil 




Small vein 


A mile from 
mouth 


Andesite 




>» ■ • 






Vein 10 ft. 
12 ft. 


§ mile from 
mouth 


., 




Blind .. 


A few " colours " 


10 chains 
from mouth 


Vein 1.5 in. 


20 chains 

from mouth 


,- 


Old prospecting- pits. 


t< 






Vein 3 in. to 
4 in. 


10 chains 

from mouth 


, 




Big Sandy Bay . . 


A few " colours " 










Old workings. Jay Could 
Claim. &c. 


Tangiaro 


»» 




"Silver lode" 
Vein 3 ft. 


1£ miles from 

mouth 
2 miles from 

mouth 


Andesite 


See description and assay, 
page 109. 


Eel . . 


Nil . . 










Shows barren chalcedonk- 
quartz. 


Kerr 


,, 












Portugese Bay . . 


„ . . 












Waikawau . . 1 














Waikanae 


" Colours " 


A mile from 
mouth 


Small vein 


£ mile from 
mouth 


Andesite 




>9 » ■ 




. . 


18 in. vein 


Ditto 


». - . 




Gisborne 


" Colours " 


A mile from 
mouth 








Veins up to 2 in. No gold 
by crushing and pan- 
ning. 


Matamataha- 


Coarse " colours " 


1 mile from 


16 in. vein 


1 mile from Andesite 


* See assay, page 110. 


rakeke 




mouth 




mouth 




Ditto .. 


•• 




Small vein 


\\ miles from „ 
mouth 




Sandy Bay 














Waihirere . . ! 


Nil 










Shows no quartz. 


Whareroa 


" Colours " 


3 miles above 
mouth 


Small vein 


3| miles from 
mouth 


Argillite 




(A) .. 


»» * . 


For ^ mile . . 


Vein 


£ mile from 
junction 


Andesite 


Blue flinty quartz. No 
gold. 


(B) .. 


>» . • 


For \ mile . . 


4 in. vein 


\ mile from 
junction 


Argillite 


Old workings. 


Mataiterangi* . . 


■■ 




Pug seam 


2\ miles from 
mouth 


99 • • 


Gives gold by panning. 


\ 


/ 




2 in. vein 


Ditto 


>> • ■ 




- 




10 ft. vein 


3 miles from 


Andesite 


No gold by crushing and 


= 








mouth 




panning. 


.. 






2 ft. 6 i n. 


3| miles from 


»» • • 


Old workings. No gold 


}f 






vein 


mouth 




by crushing and pan- 


C- 












ning. 


<D 






6 ft. vein . . 
9 in. vein 


3f miles from 

mouth 
4 miles from 


»» • • 


Assay, nil. 












mouth 







141 



Results of Prospecting Operations — continued. 



Stream. 



Detrital Gold in Debris. 



Description. 



Position. 



Quartz Veins located. 



Description. Position. Enclosing Hock 



Remarks. 



Streams flowing to the Eastern Coast-lint — continued. 



Mataiteraiigi (A) 7-8 " colours " 



(A I) 



Mangatu* 



few fine 
colours " 



Just above 
junction 



1 mile above 
junction 



5 ft. vein . 
(> in. vein 
4 ft. vein. 
4 ft. win . 
6ft. vein. 



10 chains above Argillite 

junction 
Ditto 



75 chains above Andesite till! 

junction 
So chains above „ 

junction 



Assay, nil. 

7 to 8 " colours " by 
crushing and panning. 

A few " colours " by 
crushing and panning. 



By dish, 4 or 5 " colours." 

(See assay, page 1 10. ) 



■i 



Small vein 95 chains above Quart/, ande- ( lives a few " colours " by 

crushing and panning. 
No gold by crushing and 



jtmction site 

3 ft. bin. 1 J miles above Andesite 

viiu junction 

A feu small To h o a d of 



panning. 
Ditto. 







veins 


creek 






Wairakau 


N T il .. 




.. 


• • 




(A) .. 


" ( lolonra " . . For : J mile . . 


6 in. vein 


J mile above 
junction 


Andesite 


Old workings. 


Omoho 




1 in. vein 


I j miles above 

junction 




Gives no gold on crushing 
and panning. 


.. ■ • 




T w o 3 in. 
veins 


Ditto 


.. 


Ditto. 


„ (A) . . 


" Colour- " 


■ E salt" 
leader 




Vrgillite 


* See reference, page 111. 


Mangakotukuku 




3 in. to 6 in. 




Andeeitio tulT 


(live "colours." Old work- 






veins 






ings. 



C'OROMANDEL SURVEY DISTRICT. 

Genera' Statement. — The Ooromandel Survey District covers a greater extent than any otlior survey 
district in the subdivision, and contains, with the exception of the Kuaotunu (Joldfield, all the old- 
established mining centres of the area considered in this bulletin. 

The auriferous-quartz veins are here associated with (a) the basement stratified rocks, (b) the 
Tertiary volcanic rocks of the " First Period," (c) the Tertiary volcanica of the " Second Period." 

The veins occurring in the main range in the vicinity of Tokatea Hill and Saddle, and in portions 
of the Tiki, Matawai. and Manaia areas, are referable to the old rocks (a), while those of the Hauraki, 
Kapanga, Success, Preece's Point, and Opitonui Mines and their vicinities intersect to the greatest depths 
yet exploited only the volcanica (b). The coastal belt on the western side of the peninsula consists of 
volcanic rocks of the "Second Period" (Beeson's Island Series) (c) — principally breccias and agglo- 
merates — and is certainly non-auriferous, but to the east of the divide the altered lavas and tuffs of 
this same series contain the auriferous veins of the Owera and Moewai Claims (page 131). 

The " dish prospects " of the debris of the streams Incising the ascertained mining-areas present 
no fresh significance, but the results of prospecting operations beyond these limits are of value. 

Results of Prospecting Operations. 



Stream. 



Deirita! Gold in Debl is 



Quarts'. Veins locntfd. 



Description. 



Pooi'it n. 



Defcrip'ion 



Positior. 



Enclosing Rock 



Remarks. 



Harataunga 



Creeks drain a ] 
proved auri- 
ferous area 



Streams flowing toth* Eastern Coast-line. 

1 in. vein 5 miles from Andesite 

mouth 
1 ft. vein . . Ditto . . „ 

4 ft. to 2 ft. 
quartz for- 
mation 
4 in. vein „ . . ,, 

3 in. vein „ . . „ 

1 ft. vein . . 5J miles from ,, 

mouth 



Gives gold on crushing 

and panning. 
Ditto. 



Nil. 

Gives coarse " colours " on 
crushing and panning. 



142 



Results of Prospecting Operations — continued. 



Stream 



Detrital Gold in Debris. 



Description. 



Position. 



Quartz Veins located. 



Description. 



Position. 



Enclosing Rock. 



Remarks. 



(«) 



Waikoromiko 



Waikoromiko (a) 
(b) 



(e) 
(d) 
(e) 



(/) 
(9) 

(h) 

(k) 

(m) 



Pakore 

Te Pungapunga 

Waitekuri (A) . , 



Streams flowing to the Eastern Coast-line— continued. 



Kopurukaitai . . 

„ Branch (a) 

„ (6) 

(c) 

99 99 99 

„ (d) 



" Colours 



For 30 links 



O 



Good prospect of £ mile above 

gold fork 

" Colours " . . To head 

»» • • n 

Coarse " colours" For 5 chains 



1 " colour " 



" Colours " 
Trail of gold 



Trail of coarse 

gold 
Trail of gold 



8 chains above 
fork 



To head 



Nil 



Colours 



For £ mile . . 

10 chains 

above last 
For 10 chains 

above last 
10 chains 

above last 
For 3 chains 

above last 



15 cjh a i n s 
above the 
fork 



9 in. vein 



Small vein 

2 ft. 6 in. vein 
1 ft. vein . 



6 in. vein 

1 ft. vein. . 

18 in. vein 

1 ft. vein . . 
6 in. vein 

1 ft. pug vein 
3 in. rusty 

vein 

2 in. vein 

3 ft. vein . . 
1 ft. vein . . 

Small vein 
Small veins 



2 miles above 
junction 



£ mile above 

junction 
\ mile above 

junction 
At head 
10 chains from 

head 
Near head . . 

\ mile above 

junction 
Ditto 



30 chains above 
junction 
\ mile above 

junction 
Ditto 

£ mile above 
junction 



5 ft. vein . . 

18 in. vein 
\ in. rusty 



Small vein 



10 chains 
above fork 

Ditto 

15 chains 
above fork 



Just 
fork 



above 



Andesite 



Andesite 



Coarse ande 
site breccia 
Andesite 



Andesite 



Andesite 



Old workings. 

Gold traced to a slip. 
Old workings. 



See assay, page 125. 



Gives gold on crushing 

and panning. 
Mineralised ; no gold. 



Gives gold on crushing 

and panning. 
Ditto. 



Old workings ; 1 " col- 
our " per dish on crush- 
ing and panning. 

Give no gold on crushing 
and panning. 

In the alluvium, here 6 ft. 
deep. 

Traced to old workings. 

Traced to heavy surface 

debris. 
From a pot-hole. 

Shows no gold. 



Old workings. 

Traced to heavy surface 

ddbris. 
Traced to old workings on 

1 ft. reef. 
Traced to an old drive. 
Old workings of Beresford 

Mine. 
Traced to a slip. 

Traced to a pug seam. 

Traced to old workings. 

Traced to old drive on 

pug seam. 
Traced to pug seam in 

old drive. 

Shows no trace of gold. 
Gives gold on crushing 
and panning. 



143 



Results of Prospecting Operations— continued. 



Stream 



Detrital Gold in Debris. 



Description. 



Position. 



Quartz Veins located. 



Description. 



Position. 



Enclosing Bock. 



Kemarks. 



Waitekuri (A) . 

,, (Al) 
.. (B) . 

Waingaro 
Opitonui 

Owera . . 

Mahakirau 



Howell 

Mill's ; driving 

Driving 

Hooker 

Waitakatanga . 

Day Dawn 
Sparrow 
Hooker, south . 
Waiparu 
Battery 



Mclsaacs 



Rooky 



Jubilee 



Paparoa 
Whaiwango 



Little Paul's 
Kikowhakarere 
Streams draining 
Coromandel Val- 
ley 
Waiau 

Matawai 

Tiki . . 
Pukewhau 

Awakanae 
Mill .. 



; Colours," 



Coarse " colours 



Streams flowing to the Eastern Coast-line — continued. 

4 mile above 

fork 
50 chains 

above fork 
At junction. . 



Nil 



Nil 



2 fine " colours ' 
1 " colour " 



1 coarse " oolour ' 



Nil 



1 "oo 



Above Owera 
branch (A) 

3 J miles above 

junction 

4 J miles above 

junction 

4i miles above 

junction 



2 fine " colours " At junction 
Nil .. 



Two small 

veins 
Small veins 



Flinty vein 



} mile above 

fork 
1 mile above 

junction 



Andesite 



6 " colours " 
10 



1 " colour " 



1 " colour " 



Fair " prospects 
of gold 



Nil .. 
" Colours 



Good prospects 
Nil . . 



At junction 

I mile above 6 in. vein 
junction 

J mile above 
junction 



9 in. vein 



30 chains above 
junction 



14 miles above Andesite 
junction 



1 chain from 
j u no t ion. 
No trace of 
gold above 
this point 



Streams flowing to the. Western Coast-line. 



As far as junc- 
tion of Little 
Paul's Creek 

To headwaters 



No gold in head- 
water branches 

Good dish pro- \ mile above 
speots junction 



Nil 



Show no gold. 



1J miles from mouth. 
Andesite oontains quartz 
showing pyrite ; no gold. 

* Shows no gold in creek 
above outcrop of Opito- 
nui Reef. (See page 129). 

* See referenoe to Owera 
Mine, page 132. 

* See references to Speci- 

men Terrace, &c, and 
assays, page 131. 

No quartz. 

A little quartz. 

In middle course of main 
left branoh. 

* See reference, page 130.) 

Shows some quartz. 

* Ditto. (Seepage 130.) 

* See assays, page. 130 

* Old workings. (See 
assay, page 130.) 

* Abundance of quartz 
from large " blows " on 
ridge. (See page 130.) 

Assay, 4 gr. gold, 1 dwt. 
1 gr. silver, per ton. 



* See reference, page 131. 



Little or no quartz. 
Very little quartz. 



* See reference, page 126. 

* Proved auriferous area. 



Little quartz above Mata- 
wai junction. 
* See reference, page 128 



No quarts. 



page 126. 
page 128. 



144 



Results of Prospecting Operations — contiuued. 



Detrital Gold in Debris. 



Description. 



Position. 



Quartz Veins located. 



Description. 



Position. 



Enclosing Rock. 



Remarks. 





Streams /Itm-ii"/ to 


tht Western Coast-line- — continued. 




Manaia 


1 " colour " 


.lust below 






* See reference to Golden 






Taurarahi 








Hill, page 129. 






junction 










., (A) .. 


1 coarse " colour " 


J mile above 






) 




„ (B) 


2 or 3 tine 
" colours " 


fork 
Just above 
fork 




•• 


- \ 


* See page 129. 


Taurarahi 


1 to " colours " 
of coarse gold 


For J mile 
above junc- 
tion 








* See reference to Leading 
Wind Mine, page 120. 


»» « • 


" Colours " . . For § mile 
above last 








Last " colour " at junction 
of a right-hand branch(C). 


Tupa .. 


Nil .. 








No quartz. 


Kirita 


,* • • 


" 




.. 


" 



Otama Survey District. 

General Statement. — The Otama Survey District includes within its boundaries the Kuaotunu 
mining centre and the claims of Materangi and Murphy's Hill. 

The auriferous veins of Kuaotunu occur essentially in the stratified rocks (Manaia Hill Series), but 
in places intersect also a thin capping of " Beeson's Island " volcanics ; the occurrences at Materangi 
are associated altogether with the volcanic rocks of this series, and are closely related to the Owera 
and Moewai veins of the Coromandel Survey District. 

Siliceous-sinter deposits are abundant on the Kuaotunu Peninsula, and also on the rhyolitic area 
lying to the eastward of Whitianga Harbour ; those of Black Jack Hill, Kuaotunu, contain traces of 
gold and silver, but are of no economic value. 

Results oj Prosjpectrnrj Operations. 



Stream. 



Detrital Gold in Debris. 



Description. 



Position. 



Otangaru 



(A) 



Mapauriki 

(A) . 

Streams of Kuao 

tunu Valley 
Otama 

Stewart 

Kohurahorao 

Waitaia 



Woodcock 

Whauwhau 

Akeake 

Ngarahutonoa 

Wade . . 



Purangi 
Wigmore 



" Colour " 

2 or 3 " colours 



Nil . . 

1 or 2 '" colours 



1 "[colour " 

Nil .. 
1" colour " 



Nil 



Nil .. 
" Colours " 

1 "[colour " 



Nil .. 
" Colour : 



15 chains 
from junc- 
tion 

Just above 
junction 



[ mile from 
mouth 

Near head . . 
\ mile from 

mouth 
50 chains 

from mouth 



Near head 



Quartz Veins located. 



Description. 



Position. Enclosing Rock. 



Siliceous - sin- 
ter deposit ; 
rhyolitie 



Remarks. 



Proved auriferous area. 

Upper portion not pro- 
spected. 

Formation grauwacke. 

Old workings in valley 
are said to have yielded 
specimen stone. 

Boulders of siliceous sin- 
ter, but no vein-quartz. 

* See reference, page 137. 

* See reference to Moewai 
Mine, page 132. 

* Creek - debris ; said to 
have yielded loose speci- 
mens of native bismuth. 
(See page 1(14.) 

See page 137. 



1 45 



< HAPTER XI. 



RESUME OF THE ECONOMIC POSSIBILITIES OF THE COROMANDEL SUBDIVISION. 



tPsge Page 

Introduction .. .. .. .. 145 Building and Ornamental Stones . . lis 

The Future frospecte <f Gold-silver Mining 146 Limestone .. .. .. .. 14s 

Metalliferous Deposits other than Gold-silver Coal .. .. .. .. .. 148 

Veins . . . . . . ..lis 

Introduction. 

Tin: Coromandel subdivision, compidsing an area of 30789 square miles, while primarily owing its 
economic- importance to the occurrence of gold-silver veins, is not solely dependent upon its mining 
industry. Of the natural resources other than minerals and rocks, the lands adapted Eor agricultural 
and pastoral purposes must he accorded first place. A considerable extension of the area at present 
employed for the depasturage of sheep and cattle is to he expected as the result of the deforesting of 
the lower slopes of the hilly country bordering the alluvial flats. The results which should attend 
the systematic development of these lands are likely to more Than compensate for the inevitable decline 
in the export of timber and kauri-gum. Of the marketable timber the estimated amount of kauri now 
growing in the area docs aai rxa>i>A Io.ixkumhi superficial Eeet ; other timber-trees of value for special 

purposes occur to lesser extent, but the are.i covered by lighter bush available for fuel is still consider- 
able. The amount of kauri-gum which can vet be won from the area cannot be estimated, but it is pro- 
bablv less than that already exported. 

The mineral resources of the subdivision are naturally those which more particularly fall within 
the scope of this report. These may be reviewed under the headings — 

(a.) The future prospects of gold-silver mining. 

(b.) Metalliferous deposits other than gold-silver veins. 

(c.) Building and ornamental stones 

(d.) Limestone. 

(e.) Coal. 



(a.) The Ftjtttbb Pbospei re of Gold-silver Mining- in/ihe Coromandel Subdivision. 

The attempt to forecast the future of any goldfield is not an easy task, and it will be readily conceded 
from a perusal of the preceding pages that it is almost impossible to predict with any degree of 
accuracy the future yield of the Coromandel Goldfield. 

The veins of the main mining centre (Coromandel) and its near vicinity are as irregular in their 
gold-content as those of probably any goldfield in the world. Taking any particular mine of this area, 
it is seldom or never practicable to estimate the ore-reserves of a given vein, even if development-work 
be kept well in advance of the actual getting of the ore. In the Kuaotunu centre ore-shoots of fairly 
uniform value and of considerable extent were encountered, but, of even these shoots, those already 
worked at a level of about 500 ft. from the outcrop were found to terminate with almost the same abrupt- 
ness as did most of the higher-grade bonanzas of the Cormandel centre. 
1 — Coromandel . 



146 

riie experience of the past as outlined in the historical section of Chapter II is sufficient guarantee 
for the statement that the Coromandel Goldfield is very far from depleted of its bonanza ores. Since, 
however, the actual surface of the ascertained auriferous areas has been time and again searched by the 
prospector, the location of new veins and ore-shoots must become more difficult and expensive than 
heretofore Seeing that all the great bonanzas hitherto discovered on the field occurred within a depth 
of 800 ft,. and most of them within a depth of 400 ft. of the present surface, it is probable that most 
of the bonanzas yet to be won will be derived from this same vertical zone in areas which are, owing 
to concealment of outcrops, as yet unprospected. 

In connection with the Hauraki-Kapanga-Tokatea belt, the most productive yet ascertained, 
it is almost certain that veins comparable in richness with those already exploited await discovery 
in unexplored parts of the area. As to the extent of this particular belt, McKay* writes, " How far 
this is a distinctive belt or zone of mineralised country has not, towards the south, been determined, as 
no mine-workings are extended under Kapanga Flat, and the volcanic rocks in situ are not seen at the 
surface." Prospecting of this andesitic area underlying Kapanga Flat and the Township of Coromandel 
is rendered difficult owing to the fact that alluvial deposits extend to a depth of over 100 ft. below 
sea-level. The sinking of a few boreholes might be expected to afford valuable information as to the 
character and alteration-phases of the country rock existing in this locality. Suggestions respecting 
future developments have been submitted in connection with the detailed descriptions of some of the 
individual mines on this belt. 

In regard to the various other auriferous belts and isolated areas, further discoveries in the upper 
zone may from time to time be expected. The heavy overmantle of surface debris, however, together 
with the density of the forest undergrowth, conceals rock-outcrops and renders the location of auri- 
ferous veins almost as much a matter of chance as of expert prospecting. It may here be stated that 
the detailed explorations carried out by the present survey, force the writers to the conclusion that 
future gold -discoveries in the Coromandel subdivision will be located in or near the already ascertained 
auriferous areas, and consequently that little further areal extension of these goldfields can be expected. 

The foregoing remarks, it will be observed, apply in the main only to the upper zone — that lying 
within, say, 800 ft. of the surface, irrespective of topographical features. As regards the prospects of 
obtaining payable ore from below this zone, mining operations have as yet afforded few criteria. In 
the Kapanga Mine shaft-sinking and boring has attained a depth of over 1,200 ft. in the andesitic rocks. 
Although the limited amount of work done at the 940 ft. and 1,000 ft. levels has so far proved unre- 
munerative, the prospects reported from here and from the boring operations below these levels are 
not discouraging. As already pointed out, the existence of an older land-surface at a depth of 940 ft. 
in this mine implies the possibility of ore-deposition in the underlying andesitic rocks at a period prior 
to the accumulation of the vein-bearing andesites of the upper zone, and may therefore be regarded as 
a rather hopeful feature. Should such ore-deposits be proved to exist in the Kapanga Mine, similar 
conditions may be expected in the Hauraki and other mines on this andesitic belt, since this " deep 
ground " evidently extends west to the shores of the Coromandel Harbour. 

While, however, payable ore may be expected to exist befow the 800 ft. zone in favourable horizons 
of propylitic andesites, the conditions obtaining in Cripple Creek (U.S.A.). and other districts of similar 
geological structure to the Coromandel field, suggest that the ore-shoots at the deeper levels will be 
found less numerous and of lesser dimensions than those of the upper zone. 

A consideration of deep-level mining in the Coromandel Goldfield is, moreover, concerned with the 
prospects of payable ore occurring in the old stratified rocks, which are exposed over relatively great 
areas. Furthermore, even in areas where andesitic rocks have been proved or may be expected to extend 
to considerable depths, the sedimentaries must eventually be encountered. Areas covering the old 
crateral vents, which may be considered to exist in certain undetermined localities, would, however, 
prove exceptions to this general statement. 

In only two localities in the subdivision can it be affirmed that remunerative returns have been 
obtained from mining in the basement rocks. These localities are Tokatea Hill and Kuaotunu, the ore- 
shoots in both cases being mined from the upper zone. At Tokatea the veins were associated with the 

* C.-9, 1897, page 47. 



147 

interstratified fine-grained acidic tuffs and tufaceous mudstones rather tlian with the ordinary argillites 
and grauwackes. They, moreover, evidently had upward extension into a capping of andesitic rocks 
not long since removed by denudation. These veins became impoverished with depth, and at the lowest 
level. 900 ft. below the vein-outcrop or 647 ft. above sea-level, were found to be practically valueless. 
At Kuaotunu the payably auriferous veins were almost entirely associated with the Jurassic grits, 
grauwackes, and argillites, but the principal vein — the Try Fluke — intersected at one locality a remnant 
of the andesitic capping. The ore-shoot in the vein mentioned extended from the outcrop to a depth 
of about 450 ft., or 200 ft. above sea-level. The ore-shoot of the Waitaia vein, already proved tor some 
350 ft. n vertical extent, still persists below the lowest adit, which is. however. .'500 ft. above sea- 
level. 

The two cases cited are evidence that payable gold-silver veins may exist in the basement stratified 
rocks, and in lithologically different types of these rocks. It would nevertheless appear that proximity 
to the surface or to the contact of the overlying volcanic accumulations lias constituted no negligible 
factor in the precipitation of the gold-silver content <>t these veins. 

On the whole, the prospects of deep mining in the basement stratified rocks do not appear to be 
bright, and the comparisons often drawn, by mining-men, between this goldfield and certain other 
deep-level goldfields, are scarcely admissible. As regards geological conditions, probably the Coro- 
mandel field has its nearest analogue in portions of the Dacian goldfield of south -western Transylvania. 
" At Vulkoj," in this field, says Posepny,* "the older and deeper quartzose rock carries little ore, while 
gold abounds in the overlying andesites. Several mines of the Dacian gold district have encountered 
in depth the stratified rocks through which the eruptives (Tertiary andesites, Ac.) came, and the result 
has generally been disastrous to the miner, the ore-veins having either ceased entirely or become pinched 
to barren fissures."' Since, however, the conditions governing the deposition of most gold-silver ores 
cannot yet be regarded as very clearly comprehended, a definite pronouncement as to whether or no 
pay-ore exists at any considerable depth must be left to actual mining exploration. 

Within the subdivision, the Kuaotunu or Tokatea areas, having afforded large and payable shoots 
in the upper zone of the stratified rocks, may be the firsl to receive at t em ion. At Kuaotunu 1 he further 
exploitation of the ore-shoot of the Waitaia Vine below the present levels will be followed with interest. 
Furthermore, there is some evidence that the Jurassic grits and argillites, which at the existing levels 
form the country rock of the Try Fluke vein-system, are a1 no great depth underlain by the Tokatea 
Hill Series, with its interstratified tuffs and mudstones. The sinking of one or two boreholes on the 

•u side of the Bald Spur might therefore he expected to afford valuable information regarding the 
effect of this probable change of rock-formation on these Bt rone fissure-veins, which, m the upper le> els, 
have yielded such substantial returns. In this connection, the remarks od McKay, who examined the 
Kuaotunu field when active mining was in progress, may be quoted. After review lug the evidence, 
this investigator concludes thus : "'The facts .it Kuaotunu appear to he in favour of the supposition 
that other shoots of gold maybe found at levels below those vet reached is the Try Fluke and Kapai- 
Yennont Claims ami other claims along the same line of reef." 

In the reports of Murray.t McKay,} Park.;; and Biaclaren, cited below, will be found further 
expressions of opinion regarding mining below the upper zone in this subdivision. 

In conclusion, the writers are of opinion that Coromandel will long be classed among the goldfields 
which afford ample scope rather for the speculator, who is prepared to take risks in the hope of reaping 
large profits, than for the investor who expects a regular percentage of profit on capital employed. The 
field can hope for little from improved metallurgical processes, since it possesses no workable low-grade 
ore-bodies. In view, however, of the heavy expense at present connected with pumping, winding. 
and underground exploration, even' device calculated to lower the cost of motive power or to cheapen 
in any other way the existing methods of mining must be counted a decided advantage. 



* F. V. Posepny: "The Genesis >>f Ore-deposits," Trans. Am. Inst Slin. Eng., vol. xxiii, 1893. Reprinted by 

same Institute in •' The Genesis of Ore-deposits," 1902, page 88. t. Murray: CO, 1894, page 4. t McKay : C 9, 

ls'aT jjPark: "Geology and Veins of Hauraki Goldfield, 1897"; ".Votes on the Geology ol The Kuaotunu 

(U ldfield," Trans., vol. xxvi, page 360. . Maclaren: C-9, 1900. 



148 



(h.) Metalliferous Deposits other than Gold-silver Veins. 

In previous chapters of this bulletin reference has been made to the occurrence of ores of lead, 
copper, antimony, and bismuth. The prospecting operations of the past, however, have not been 
successful in ideating deposits (if any of these ores in payable quantities. 

The galena-chalcopyrite lode of the Petote and Tiki Creeks, though in the present mine-workings 
rather small and lenticular, may yet prove of some economic value. A huge boulder of this ore dis- 
covered some years ago in Tiki Creek would indicate that the veins may at some undiscovered point 

in greater dimensions than at the localities worked. 

Ore containing a high percentage of antimony in the form of stibnite has been found as boulders 
in the little-explored Upper Mahakirau Valley. A picked sample from the veins already located gave on 
analysis only 966 per cent, of the metal. 

Metallic bismuth was found in the debris of Wade Creek (Mercury Bay), but the source of the erratics 
has not yet been located. 

(c.) Building and Ornamental Stones. 

Building and ornamental stones occur at two widely separated localities in the subdivision. The 
quartz diorite of the western flank of Moehau Bange is the most valuable of these stones, being almost 
equal to the best granites for architectural purposes and for heavy masonry-work. 

Stones of very different textural character are afforded by the pumiceous rhyolitic tuffs of Whitianga. 
One variety of these tuffs, a pinkish-grey rock, has well withstood the test of twenty-five years' service 
as wharf-piers and building-foundations. Another variety, resembling the white calcareous Oamaru 
stone, occurs in considerable abundance, and is of value for special purposes. The spherulitic rhyolite 
of Purangi may prove on exploitation to afford a handsome ornamental stone. 

(d.) Limestone. 

Since limestone is not known to occur elsewhere in the Hauraki Peninsula, the deposits of this 
rock exposed at Torehine and Branch Creek are of some commercial value. 

At Torehine the limestone (containing 85 - 7 per cent. CaC0 3 ), though of somewhat limited 
extent, is easily accessible, and likely to be employed for metallurgical purposes within the Hauraki 
goldfields. At Branch Creek, which, however, is situated some four miles from the sea-border, a 
much greater quantity of limestone is available than exists at Torehine. 

(e.) Coal. 

Coal is known to occur in association with the beds of the Torehine Series at several localities in the 
subdivision ; but the limited extent and inaccessibility of the deposits precludes its being regarded as 
of any economic importance. 



149 



INDEX. 





A. 


Tape 


Blechnum priscum 
Bornite 




PftRe 
54 


Aoidio intrusives 




94 




103 


„ lavas 




23 


Branch Creek 




34, 53, 54, 56 


. tuff8 . . 


.. 23, 43, 45, 


83-87, 93, 101. 129 


Bremner's tunnel 




74 


Acknowledgements 




3 


Britannia Mine 




70, 72, 73, 74 


Adinole 




.. 44,45 


Bronlund Creek 




33 


Age of various geological 


formations. 


See Table 


Bryozoan corals 




54 


of Contents. 






Buffalo beach 




37, 61 


Agricultural statistics 




19 


Building stones 




. . 96. 148 


Agriculture 




19 


Bunker's Hill Mine 


. . 17. 


Ahirau Bay 


. 


34 








Aitken Creek . . 




126 








Akeake Creek . . 




37 








Alethopteria 




54 


C. 






Altered rhyolites 




43 






Analyses 


.. 44,56,57 


, 64, 70, 71, 73, 74, 


Cabbage Bay . . 2, 8, 12, 13, 20, 


31, 32, 


46, 53, 60, 61, 76 


See also Assays. 




[82, 87, 90, 93, 95 


-Waiau section of main divide . . 29 


Andesites 




24, 52, 63, 65, 73 


Cadman Creek 




. . 42, 45 


. Intrusive 




92 


Calcareous sandstone 




. . 22, 56 


Andesitic rocks 




23 


Calcite 




102 


Anthony Creek 




35, 53, 56 


Cape Colville 




21, 27, 53, 58 


Anticlines 




24 


Range 




. . 29, 30 


Antimonite 




104 


Carbonaceous bands 




. . 25, 66 


Antimony 




148 


Cardium 




54 


sulphide 




104 


Carey's Bay 




79 


Aorere Claim . . 




136 


Carnelian 




102 


Aragonite 




102 


Castle Hock 




8, 29, 30, 36, 88 


Area described in the Bu 


letin 


2 


dyke 


34 


36, 65, 73, 89, 92 


Argentine 




102 


Mine 




.. 128, 129 


Argentite 




103 


Chalcedony 




102 


Argillites 


22, 23, 


Cbalcopyrite .. 




. . 103, 148 


Arsenic 




104 


Cinnabar 




103 


Arsenolite 


, . > 


104 


Circulation-channels 




. . 99-100 


Arsenopyrite .. 




103 


Climate 




7 


Assays . . 108, 


109, 110, 120, 


125, 126, 127, 128, 


Coal 




148 


See also Analyses. 


[130, 131 


, 132. 135, 136, 137 


„ -bearing strata 




23 


Auckland 


7, 


8, 9, 13, 14, 20, 21 


„ -seams 


23, 


24, 25, 64, 78, 116 


Augite 




69 


Coast-line, Features of 




.. 31,32 


and'site 




71 


Ccelenterata 




54 


Austral Hill . . 




70 


Colville, Cape 




2,21 


Road . . 




. . 53, 57 


. Peninsula 




.. 27,28 


Auriferous belts 




.. 107-108 


Range 




. . 29, 30 


Awakanae Creek 




35, 50, 59, 72 


Survey District . . 




2, 27, 46, 138 


Azurite 




104 


Veins of 
Communication, Means of 




108 
.. 13,14 








Conglomerate . . 22, 23, 24, 


48, 49, 


51, 53, 55, 58, 88 




B. 




Cook, Captain 




5 






Creek 




37 


Bald Spur 




108, 133, 134, 137 


Cook '8 Bay 




21, 31, 32, 37, 61 


, Gold and silvc 


r returns . . 


134 


Copper 




18, 103, 148 


Bambusites australis 




54 


Copperas 




103 


Barnev Creek . . 




. . 34, 64 


Copper carbonate 




104 


Bat (New Zealand) 




1 


pyrites 




103 


Battery Creek 




130 


Coralline limestone 




56 


Bay View Mine 




111 


, structures 




46 


Beaches 




30, 60, 61 


Coromandel 




12, 35, 60 


Beeson's Island 




30, 32, 38, 75, 78 


Gold Company 




.. 16,112 


Series 




23, 30, 47, 75-83 


Harbour 


"30, 


32, 35, 61, 65, 66 


Belemnite 




. . 49, 50 


mining centre 




14, 15, 16 


Big Paul's Creek 




35, 41, 71 


Peninsula 




27 


. Reef 


1 1 i 


12,43, 105, 119-121 


subdivision . . 




2 


. Sandy Bay Creek 




34 


Survey District 




2, 66, 141 


Birds (native) 




4 


Valley 




19, 35, 66 


, (introduced) 




5 


Courthouse Creek 




42 


Bismuth 




104, 144, 148 


Cousin Jack Creek 




.. 51,110 


Blackmore's Mine 




45 


Crater 




78 


Black Jack 


• 


30, 133, 136 


Cripple Creek. . 




2 


Blagrove's Freehold 




17 


Cucullaa 




54 



11 — Coromandel. 



150 



Culture 
Cuvier Island 



D. 



Dacitic rocks 

Dacre Hills .. 

Darkie Creek 

Day Dawn Claim 

Deep-level mining 

Denudation (sub-aerial) . . 

Dews 

Diorite 

porphyrite 
Distribution of the veins. . 



Page 
12 

8 



23, 63, 65, 66, 73, 83, 92 

.. 77,83 

31, 34, 90 

131 

147 

24 

7 

.. 24,49,52,89,90 

90 

. . 107-8 



E. 



Eartb-movements 


24,25,61 


Echinodermata 


54 


Elevation of land 


31 


Eocene (lower) strata 


..23,55 


Epsomite 


102 


Erubescite 


103 



F. 

Fagus, sp. . . 

Fantail Creek 

Faults • 

Fauna 

Field-work (method of conducting) . . 

Fish 

Fishing 

Flabellaria sublongirachis 

Flabellum 

Flats 

Flax 

Flax-mills 

Flax-mill Creek 

Flora 

Flounder 

Flow-breccia 

Fluviatile deposits 

Fluvio-marine deposition 

Folding (Jurassic) 

Foliated a^gillite 

Foraminifera 

Fossils 

Jurassic 

of the lower Miocene 

„ Manaia Hill beds, Report on the 
Torehine Series 
Four-in-Hand Battery 

Mine .. 18,66,70,101 

Frog (New Zealand) 
Fusus 
Future prospects of gold-silver mining 



G. 



Galena 

Geography, physical 

Geological history 

structure 

Gisborne Creek 

Glauber s salts 

Gold 

Golden Anchor Claim 
Buiterfly 
Hill Cairn 
Pah Mine 

Gold-production 

Gorges 

Gravels 



17, 91 



Grauwacke 

Great Barrier Island 

Great Mercury Island 

„ Mining Claim 

Green Harp vein 
Green Hill 
Grits 

Gum, Kauri 
Gurntown 



H. 



Page 

22, 24, 43, 48, 52 56 

1, 2, 8. 27, 109 

1, 2, 4, 8 

16, 17, 134 

15, 16, 113 

42 

24, 48, 49, 52 

5, 20 

14 



54 

34 

99, 114 

4 

3 

5, 21 
21 
54 
54 
60 

6, 21 
21 
37 

5, 6 

21 

. 64, 81 

. 59-60 

31 

24 

52 

54 

22 

29, 49, 50 

76 

. 49-50 

54 

72 

108, 124 

4 

55 

145-147 



104, 148 

29 

23 

25 

110 

102 

102 

136 

102 

129 

111, 115 

18 

33, 35 

24 



Haematite 








103 


Haudsworth Claim 








134 


Hanging Rock 








79 


Hapuka 








28 


Harataunga River 








34, 42, 46, 72 


„ Survey District 




2, 27, 


53, 66, 109, 139 




Veins of 


109 


Harbours 






13 


Harbour View Mine 






123 


Hartridjje's vein 






117 


Hauraki Associated Mine 






45 


Division 






1, 2 


Freehold Mine . . 






.. 18,115 


Gold-mining Company (Li 


mited) 


17 


group of mines 






107 


Gulf 






.. 1, 21, 27 


Mine 17, 18, 


74, 91, 


101, 106, 


„ mining district 






2, 84 


No. 2 Mine 






.. 17,115 


Peninsula 








. . 27, 46 


South Mine 








115 


special area 








111 


Hedyphane 








104 


Hemipatagus tuberculatu 


! 






54 


High-level terraces 








59 


Hikurangi 








30 


History, Geological 








23 


History of gola-mining 








14-18 


Holland Creek 








33 


Hooker Creek 








79 


Hope Creek 








31, 34, 47, 108 


Hornblende . . 








69 


„ andesite 








72, 73, 83, 92-3 


porphyrite 








. . 90-91 


Horn-silver 








103 


Hosie's Saddle 








42 


Hot springs 








. . 37, 85 


Hot Water Beach 








. . 2, 37, 85 


Huaroa Creek 








60 


Hukurahi 








30 


Hurewai Creek 








33 


Hyalopilitic matrix 








67 


Hydrothermal action 








25 


Hypersthene 








68 


„ andesite 








70, 71, 81, 82 



Igneous rocks 

Iltneuite 

Industries 

Inoceramus 

Insects 

Intrusive igneous rocks 

Invicta Claim 

Irene Claim . . 

Ircn, Hydrous oxide 

„ oxide 

„ pyrite . . 
Islands 

„ Great Barrier 
„ „ Mercury 



. 62-97 

103 

19 

49 

4 

22, 87-94 

135 

17 

103 

103 

103 

32 

1 

1 



151 



Jasper 

Jersey Creek . . 
Jubilee Cre*k 
Jurassic folding 

, fossils 
Just-in-Time vein 



Paee 

102 

110 

131, 143 

24 

22 

134 



K. 



Kabikatea 


. . 6, 8, 20 


Kaimarama River 


19,31,35 


Kaipawa 


. . 8, 29, 66 


Kairaumati Creek 


46 


Kaolin 


102 


Kapai-Vermont Claim 


.. 134, 147 


Kapanga Flat 


146 


group of mines 


107 


Mine . . 15, 


17, 18, 25, 66, 71, 99, 101, 




115, 146 


mining-area 


115 


North Mine 


72 


abaft 


..66, 116 


Karaka Stream 


. . 35, 69 


Karangahake Mountain 


68 


Kathleen Crown Mine 


.. 17,93 


Mine 


. . 60, 74 


Kauri 


5, 6, 8, 20 


Freehold Gold Estates 


16,17,129 


,. gum .. 


5,30 


, exported 


20 


Kawhia beds 


. . 49, 50 


Kennedy's Bay 


2, 12, 13. 14, 19, 29, 31. 




47, 51,60,61, 79, 81 


flats 


31 


Kerargyrite 


103 


Kermesite 


104 


Kerr Creek 


.34,81 


Kevin Point 


. . 65, 107 


Kikowhakarere 


82 


Stream 


35 


Killarney vein 


110 


Kmg-country 


84 


Kirita Bay 


2, 13, 30, 35, 80 


Creek 


35 


Kohurahorao Creek 


37 


Kopurukaitai .. 


34, 66, 72 


Koputauaki 


19 


Bay 


.. 81,89 


Kuaotunu 


18, 14, 52 


Beach 


61 


Goldfield 16, IS 


, 101, 105. 132, 133. 145-7 


Peninsula 


27, 30, 37, 51, 77, 79, 80 


Stream 


.. 36, 188 


vein 


134 



Lacustrine deposits 
Lamiia huttoni 
Lanigans vein 
Lead 

Leading Wind Claim 
Lead sulphide 
Legge's Reef . . 
Limestone 
Limonite 
Literature 
Little Barrier 
Little Paul's Creek 
Littoral deposits 
, zone . . 



Macaronic Gully 

Maddern Creek 

Mahakirau River 

Mahinapua 

Maiden Mine . . 

Main divide . . 

Maitai rocKS . . 

Malachite 

Mammals (introduced) 

Manaia 

Harbour 

Hill . . 
» Series 



M. 

Page 

110 

42 

19, 31, 85, 39, 66, 71, 72, 130, 148 

61 

71, 91, 105, 129 

28 

. . 41, 46 

104 

5 

12, 13, 19, 60, 79, 108, 129 

30, 31, 32, 35, 61, 77, 80 

41. 48, 49 

22, 24, 25, 26, 41, 42, 47, 48-52, 66, 

77, 88, 89, 91, 92, 93, 101, 129, 133 

See also Table of Contents. 

Manaia River.. .. 35, 36, 39, 42, 43, 45, 46 

Valley .. .. .. 129 

Manakau . . . . . . 76 

Mangatawbiri . . . . 30 

Mangatu .. .. 34,47,51,70,110 

Mangroves .. ..5,61 

Manuka . . . . . . 6 

Maoris . . . . . . . . 13 

Mapauriki . . . . 36 

Marcasite . . . . . . 108 

Marine beds (Torehine Series) . . . . 56 

Mariposa Claim .. .. ..16,17 

New Claim . . . . 17 

Marl . . . . . . 24, 83 

Marly sandstone . . . . 23, 56, 58 

Mataiterangi .. 34,47,51,111 

Matamaiaharakeke .. .. 34,61,65,70,110 

Veins of . . .. HO 

36, 42, 47, 50 

36 

128 

..79,81 

108,131,132 



Matawai Creek 

Falls 

Valley 
Materangi Bluff 
Claim 
Hill 
Matrix of volcanic rocks 
Megascopic characters of the volcanics 
Melanterite 
Meicury Bay . . 

springs 
Mercury sulphide 
Metallic minerals 
Micropa'cilitic matrix 
Mill Creek 
Mimetite 
Mineral heads 
Mineralised rhyolites 
Mineralising agents 

Mineralogy of the ore and gangue minerals 
Mineral production 



Loosely consolidated and unconsolidated debris 

Look-out Rock 

Lowlands 



60 

55 

16 

.. 18,148 

129 

104 

.. 17,113 

23, 24, 56, 148 

103 

9,11 

8 

35, 126, 143 

. . 60, 61 

61 



Minerals 
Mirabilite 
Mispickel 
Moanataiari Mine 
Moehau Mountain 
Range 

Series 



59 

29 

28, 30 



See also Table of Contents. 
Moehau section of main divide 
Survey District . . 

Veins of 
M ewai Mine 
Mollusca 

Monte Cristo Mine 
Motutere 

Movements of shore-line . . 
Muds 
Mudstones 
Mullet 
Murphy's Hill Min6 



82 

. 67, 80 

67, 80 

103 

5,12, 13, 30, 31, 32,60,61, 77 

37 

103 

. . 102, 105 

68 

35 

104 

. . 122-3 

128 

100 

. 101-104 

18 

.. 102-105 

102 

103 

107 

5, 6, 8, 34, 65, 88, 89 

3, 29, 33,34,40, 46, 47, 

57, 90, 96 

22, 23, 24, 25, 26, 41, 42, 

46-48,49, 88, 89, 91, 92 



28 

2, 27, 46, 92, 108, 138 

108 

108, 131, 132 

54 

45, 46, 124 

29, 30, 35, 36, 88, 92 

24 

24 

43, 45, 48 

21 

108, 131, 132 



152 



N. Ps * e 

Neilson Creek . . 34, 53 

New Hauraki Gold Properties (Limited) . . 17, 120 

New Mmt Claim . . . . • • 136 

Ngakuku Creek .. .. .. 110 

Ngarahutonoa Creek .. .. ..131,132 

Nickel .. •• •• •• 104 

Non-metallic minerals . . . . . . 102 



O. 

Oamaru limestone . . . . . . 97 

Officers connected with field-work . . . . 2 

Ohinewai Creek . . . . 34, 90, 109 

Old Kapanga Cla'm 
Old Scoity's Claim. 
Olivine 



See Kapanga Mine. 
See Scotty's Mine. 



Omaro Spit . . 
Omoho Creek . . 
Ongahi Creek . . 
Opito 
Opitonui Creek 

Saddle 
Ore-shoots 
Ore and gangue minerals 
Origin of the gold and silver 
Orogenic movements 
Orpiment 
Orua 

, Hot Spring 
Ostrea wullerstorfii 
Otama 

Claim 

Survey District . . 
Otanguru Creek 
Outline of geology 
Outlying ridges of the main divide 
Owera Creek . . 
, Mine . . 
„ Veins of 
Oxidation 
Ojster 



Pa Hill 

Pakawau beds (Nelson) . . 

Palaeontology. See Fossils. 

Paparoa 

Creek 
Paul's (Big) Creek 

(Little) Creek 
Periods of mineralisation 
Pentacrinus stellatus 
Petote Creek 
Peverii Mine 
Pdysical geography 
Physiographic features . . 
Pigmy Mine 

Pilotaxitic matrix (andesites) 
Pinnacle Rock 
Pleistocene deposits 
Pohutukawa 
Population 
Porphynte 
Pori Charles . 
Port Jackson . 
Pot-holes 
Preece's Point 



34, 42, 47, 53, 54, 58, 64, 
31,34 



16, 17, 34, 71, 79, 
'. '. 106, 



2, 12, 13, 14, 19 



Mine 

special area 
Pre-Jurassic and Jurassic sedimentary 
Pride of Tokatea Mine . . 
Prop^litisation 

Prospecting operations by Survey 
Pukewhakataratara 
Pukewhau 



69 
31 
111, 141 
, 60, 109 
60 
108, 129 
29,91 
107, 113 
101-105 
107 
24,40 
104 
37 
38 
54,56 
61 
134 
144 
36 
22 
28-30 
20, 36 
81, 108, 131, 132 
16, 132 
105 
31 



73 
55 

19 

35, 50, 52 

35, 41, 71 

35, 126, 143 

98 

54 

98, 126, 148 

45 

27 

27, 28 

42 

67 

30 

23, 26 

5, 20 

13 

24, 49, 52, 90, 92 

30, 31, 34, 78, 79, 80 

14, 31, 47, 61 

33 

60, 65, 66, 70, 71, 108 

17 

125 

rocks . . 40, 54 

123 

69, 74, 75, 100 

138-144 

8, 30, 77 

41, 45, 50, 59 



Pukewhau Saddle 
Purangi Creek 

Estuary . . 
, special area 

Puriri 

Putataka beds (sequence) 
Pumiceous tuffs 

, agglomerate . . 

, breccias 

Pyrargyrite 
Pyrite 
Pyrolusite 
Pyroxene andesites 
porphynte 



Quartz 

Quartz-biotite diorite 
Quartz diorite 
^uartz-sericite rocks 
Queen of the North Claim 



Q. 



Page 

42, 50, 52 

37 

61 

137 

6, 20 

50 

83-85, 97 

83-86 

86, 97 

103 

69, 103 

104 

71, 72, 82, 92, 93 
92 



43, 52, 69, 102 

89, 90, 96 

. . 90, 96 

.. 43,45 

124 



R 

Rainbow reef . . . . . . 103 

Rainfall .. .. .. .. 7 

Raised beaches . . . . 31, 60, 61 

Rangatira Claim .. .. .. 64 

Ringipukea Island .. .. .. 78 

Rata . . . . . . 6, 20 

Realgar .. .. .. .. 104 

Recent deposits .. .. 23,59,60,61 

tied Mercury Claim . . . . 16, 134 

Report on fossils of Manaia Hill beds . . 49-50 

Resume of economic possibilities . . . . 145-148 

Rewarewa . . . . . . 6, 20 

Rhodochrosite .. .. .. 104 

Rhodonite .. .. .. .. 104 

Rhyolite intrusives . . . . . . 94 

Rhyolites, Mineralised .. .. .. 126 

Rhyolitic rocks . . 23, 24, 43, 45, 49, 52, 63, 

64, 65, 83-87, 126, 128 



. 6, 8, 20 

13 

100 

. 31, 88 

71 

1, 84, 100 

107, 121 



Rimu 

Roads 

Rock-alteration connected with mineralisation 

Rock shelves 

Rocky Creek 

Rotorua 

Royal Oak group of mines 

Mine . . 17, 18, 43, 45, 91, 99, 100, 

105, 106, 119, 121, 122 

Ruby, silver .. .. .. .. 103 

Ruffin Peninsula . . . . . . 77 



s. 



Sand-dunes 
Sandstones 
Sea- be aches .. 

„ caves 
Scenery 
Schnapper 
St-otty's Mine 
Semi-basic igneous rocks 
Sequence of formations 
Settlements . . 
Shakespeare Cliff 
Shales 

Siliceous sinters 
Silver 

glance . . 

lode 

-production 
Sinters. See Siliceous sinters 
Sorry Mary Creek 



Intrusive 



31, 33, 37, 61 

23, 53, 56, 58 

.. 31,61 

32 

8 

21 

15, 17, 66, 73, 117. 118 

. . 87-94 

22 

. . 12, 13 

. . 32, 85 

23, 24, 53, 55, 57 

25, 85, 102, 135, 136, 137, 144 

103 

103 

72, 99, 140 

18 



89, 108 



153 



Sparrow Creek 
SpberuHtic rhyolites 
Bpotted adinole 
Springs, Hot . . 
Cold . . 
Stewart Creek 
Stibnite 
Stony Bay 
Streams 
Structure of the several rock-formations 

See also Table of Contents. 
Structure of the vein-material 
Subdivisions of Hauraki Quadrangle 
Succession of lavas 
Success Hill . . 

Veins of 
Success Mine . . 
Road . . 
Sugar Loaf Rocks . . 47 

Sulphate of iron 
Survey districts of Coromandel subdivision 



Talus and wind-blown deposits 
Tandem Mine 
Tungiaro Creek 
Taputapu Creek 

Hot Spring 
Taurarahi Creek 
Tawhetarargi Creek 
Te Aroba Mountain 
Te Kouma Harbour 
Teleihore Mine 
Tellurium 
Temperature .. 
Te Pungapunga Creek 
Valley 
Te Ratga (Look-out Rock) 
Terraces 
Tertiary volcanic rucks of 



Page 










Page 




71 


Tribute vein . . 








. . 15, 100 


85, 86, 


148 
44 


Trig. Hilt 
Triumph Mine 








29 
. . 66, 126 


'. '. 37 


, 85 


Trout 








5 




38 


Try Fluke Claim 






16, 


17, 134, 147 


.' .' 53 


,58 


vein 




16, 


105, 


133, 134, 147 


.. 104 


148 


Tuatara lizard 








4 


31, 34 


, 46 


Tufaceous inudstone 






43, 


45, 101, 129 


35 


-37 


Tupa Creek . . 








. . 36, 72 


2c 


-26 

105 

2 

95 

29 


Tun itella 

Tutahoa Creek 


u. 






. . 54, 55 
50 




124 


Umangawha Creek 33, 34, 46 


47, 


53, 54, 56, 64, 119 


17, 66, 73, 


108 
42 

, 83 


I'nio 








60 


, 76* 78, 81 














103 














2 


Vaughan's Claim 
Vein fissures . . 
Veins 


V. 






128 
. . 99-100 
. . 98-137 






See also Table of Contents. 










61 


Venus 








54 




124 


Victoria Claim 








129 


4, 72, 109, 


140 
37 


Vizard's Claim 
Volcanic crater 








. . 128, 129 
.. 77,79 




37 


rocks (Tertiary) 


of the " 


First Period" 



36, 66, 129, 144 

. 35, 48, 49, 52, 53, 55, 56 

6, 7 

8,32,61,77 

112 

104 

7 

20, 34, 61 

2 

8. 29 

. . 59, 61 

' First Period " 

23. 20. 54, 63-75, 91-93, <J0. 129 
Tertiary volcanic rocks of " Second Period " 

23, 26, 33. 53, 54. 65, 75-83, 91, 93, i)6 
Tertiarv volcanic rocks of "Third Period" 

38, 26, 83-87, 96 
Tetrahedrite .. .. .. .. 104 



Te Tutu 

Thames 

Thomas Prof. A. VV. P., 

Tiki Creek 

. Flat 

. Hill 
Tiki - Mercury Bay Road 
Tiki-Ooitonui Road 
Timber 

Titanium dioxide 
Tokatea " Big Reef" 
Hill .. 

.. Series 



See alio Table of Contents. 
Tokatea Mme 
, Saddle 

-Success Range 

vein . . 
Tonapah (U.S.A.) 
Torehine 

Series 
Totara 
Towns 
Tracks 

Transylvania . . 
Trealease's Point 
Tribute lode (Bunker's) 



30, 79, 81 
.. 1. 2, 14 
Report on fossils by . . 

16, 36, 41-43, 45, 59, 126, 148 

36 

14, 52, 108, 128 

59 

. . 42, 45 

20 

103 

42, 43, 105, 119-121 

8, 14, 15, 29, 42, 43, 45, 

94, 107. 121, 146, 147 

22-26, 35, 30, 41-6, 47-9, 

51, 62, 65,66,87,88,89, 

91, 92, 94, 95, 109, 129 



24, 63-74 
" Second Period " 

25, 53, 75-83 
"Third Period " 

25, 83-86 



w. 



17, 43, 122 

29, 65, 94 

119 

15 

2 

53-55 

23, 24, 25, 34, 53-8, 64, 83, 93 

. . 6, 8, 20 

12 

13 

2 

84 

114 



Wad 

Wade Creek 
Waiaro 

. coal 
Waiau Palla 

Waiau - Cabbage Bay i-ection 
-Mahakirau 
River . . 
Saddle 
Valley 
Waihi 

Mine . . 
Waihirere Creek 
Waikanae , 
Waikawau 

flats 
Waikoromiko Creek 

special area 
Waiparu Creek 
Wairakau 
Waitaia Creek 
Hill . 
Mine 16, 17, 

Ridge 
Waitakatanga Creek 
Waitekuri 
Waitemata beds 
Waterfalls 
Water-power . . 
Waverley Creek 
Welcome Find Claim 
West Tokatea Claim 
Whaiwango Creek 
Whangapoua . . 

Claim 
flats 
„ Harbour 

Saddle 



13, 19, 31, 34, 53, 54 

of main divide 
15* 31, 35, 36, 39 
. . 19, 47 

14, 19, 21, 34 
34, 42 



55,57 



42, 50 
. 29 

O'J, 60 
2 



34 
51, 61 

46, 66 
. 18, 



18, 37, 45, 51, 133, 135, 

42, 45, 51, 108, 133, 

35, 36, 66 



.. 33 
. 38 
34, 42 



35,41,45 

2, 12, 13, 14, 17, 19, 

60, 61, 65, 71 

.. 108, 

'. '. 30 



104 

148 

,60 

57 

36 

29 

29 

, 52 

36 

72 

63 

1 

82 

72 

72 

31 

,72 

124 

130 

34 

37 

30 

147 

135 

,71 

34 

76 

, 36 

,39 

,43 

115 

123 

, 71 

21, 

. 72 

125 

31 

,31 

29 



12— Coromandel. 



154 



Wbangarahi Creek 

Whareroa 

Whauwhau 

, special area 

White iron pyrites 

Star Cietk 
Wliitianga 

Estuary 

Plat 

Rock 
Wigmore Creek 



L9 



Page 
14, 31, 35, 59, 74 
33, 34, 51 
108 
137 
103 
110 
. . 20, 21 
20, 30, 32,35,61, 83 
30 
. . 85, 97 
. . 32, 37 



Wigmore Hot Spring 

Winds 

*' Wilsonite " . . 

Woodcock Creek 



Zinc 



blende . 
sulphide 



Page 

37,38 

7 

86 

37, 137 



18 
104 
104 



By Authority : John Mackay, Government Printer, Wellington. — 1907. 



(2,500/8/07-«402 






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